•  ;  CATALYSIS  ,,•••;'•';'•:• 

IN 

ORGANIC  CHEMISTRY 


BY 

PAUL   SABATIER 

MEMBER  OF  THE  INSTITUTE 
DEAN  OF  THE  FACULTY  OF  SCIENCES  OF  TOULOUSE 


Translated  by 
E.   EMMET  REID 

PROFESSOR  OF  ORGANIC  CHEMISTRY 
JOHNS  HOPKINS  UNIVERSITY 


NEW  YORK 

D.  VAN  NOSTRAND  COMPANY 

EIGHT  WARREN  STREET 

1922 


COPYRIGHT;  1922 

BY  D.  VAN  NOSTRAND  COMPANY 


Printed  in  the  United  States  of  America 


PREFACE 

BY  his  remarkable  investigations  on  catalysis,  Professor  Sabatier 
has  opened  up  new  fields  rich  in  scientific  interest  and  fruitful  in 
technical  results.  Catalytic  hydrogenation  will  ever  be  an  important 
chapter  in  chemistry.  He  is  a  teacher  as  well  as  an  investigator  and 
has  done  an  important  service  in  collecting  from  scattered  sources  a 
vast  amount  of  information  about  catalysis  and  bringing  the  facts 
together  in  convenient  and  suggestive  form  in  his  book.  I  deem  it 
a  privilege  to  render  his  masterly  work  more  accessible  to  English- 
speaking  chemists. 

The  text  and  the  unsigned  footnotes  represent  Professor  Sabatier  rs 
work  as  closely  as  I  can  make  them.  I  have  retained  the  charac- 
teristic italics.  I  have  added  a  few  notes  which  are  signed  by  those 
responsible  for  them.  In  this  connection  I  wish  to  thank  my  friends, 
among  them  Dr.  Gibbs,  Dr.  Ittner,  Dr.  Adkins,  and  Dr.  Richardson, 
for  assistance,  Professor  Gomberg  for  verifying  a  number  of  Russian 
references,  and  Professor  H.  H.  Lloyd  for  aid  in  proofreading. 

To  the  chapter  on  the  theory  of  catalysis,  I  have  added  an  illumi- 
nating extension  by  Professor  Bancroft,  Chairman  of  the  Committee 
on  Catalysis  of  the  National  Research  Council.  In  order  to  make 
the  vast  amount  of  detailed  information  in  the  book  more  readily 
available,  I  have  prepared  a  subject  index  of  some  seven  thousand 
entries  and  an  author  index  of  about  eleven  hundred  names. 

It  is  a  pleasure  to  present  a  brief  sketch  of  his  life  and  abounding 
activities. 

I  have  taken  great  pains  to  check  the  hundreds  of  references,  but 
doubtless  errors  will  be  found.  Corrections  of  any  kind  will  be 
appreciated  if  sent  me. 

E.  EMMET  REID. 

JOHNS  HOPKINS  UNIVERSITY, 
BALTIMORE,  MD. 
August,  1921. 


500  Ml 


TABLE  OF  CONTENTS 

[References  are  to  Paragraphs] 

CHAPTER  I 
CATALYSIS    IN    GENERAL 

DEFINITION   OP   CATALYSIS    1 

HISTORICAL 4 

DIVERSITY  IN  CATALYSIS   5 

Homogeneous  systems   6 

Heterogeneous  systems    7 

AUTOCATALYSIS       8 

NEGATIVE  CATALYSIS  9 

Stabilizers  13 

Reversal  of  Catalytic  Reactions  14 

Reversible  reactions,  Limits  19 

Velocity  oj  Catalytic  Reactions  23 

Influence  of  Temperature  24 

Influence  of  Pressure  30 

Influence  of  Mass  of  Catalyst  32 

CHAPTER  II 
ON    CATALYSTS 

Solvents 36 

DIVERSE  MATERIALS  CAN  CAUSE  CATALYSIS  41 

Elements  as  Catalysts  42 

Non-metals     43 

Metals    . . , 50 

Nickel,  Conditions  of  Preparation   63 

Copper     59 

Platinum,  Various  Forms  used   61 

Colloidal  Metals,  Methods  of  Preparation  67 

Oxides  as  Catalysts   73 

Water     73 

Metallic  Oxides    75 

Influence  of  their  Physical  State   76 

Mineral  Acids   81 

Bases    83 

Fluorides,  Chlorides,  Bromides,  Iodides  84 

Cyanides     95 

Inorganic  Salts  of  Oxygen  Acids  96 

Various  Compounds    104 

DURATION  OF  THE  ACTION  OF  CATALYSTS  Ill 

Poisoning  of  Nickel   112 

Poisoning  of   Platinum    116 

Fouling  of  Catalysts   118 

Regeneration  of  Catalysts   123 

Mixture  oj  Catalysts  with  Inert  Materials  126 

vii 


viii  CONTENTS 

CHAPTER  III 
MECHANISM    OF    CATALYSIS 

Ideas  of  Berzelius   129 

Physical  Theory  oj  Catalysis 131 

Properties  of  Wood  Charcoal  131 

Heat  of  Imbibition  133 

Absorption  of  Gas  by  finely  divided  Metals  135 

Physical  Interpretation  of  their  Catalytic  Role  138 

Insufficiency  of  the  Physical  Theory  141 

Chemical  Theory  of  Catalysis  145 

Reciprocal  Catalysis  146 

Induced  Catalysis  149 

Auto-oxidations  150 

Oxidation  Catalysts  152 

Catalysis  with  Isolatable  Intermediate  Compounds  156 

Action  of  Iodine  in  Chlorination  156 

Catalysis  in  the  Lead  Chamber 158 

Action  of  Sulphuric  Acid  on  Alcohols  159 

Method  of  Squibb  161 

Use  of  Copper  in  Oxidations  162 

Action  of  Nickel  on  Carbon  Monoxide  163 

Catalysis  without  Isolatable  Intermediate  Compounds  164 

Hydrogenation  with  Finely  Divided  Metals 165 

Dehydration  with  Anhydrous  Oxides 169 

Decompositions  of  Acids  171 

The  Friedel  and  Crafts  Reaction  173 

The  Action  of  Acids  and  Bases  in  Hydrolysis 175 

Advantages  of  the  Theory  of  Temporary  Combinations  180 

Theories  of  Catalysis  by  W.  D.  BANCROFT  180a 


CHAPTER  IV 

ISOMERIZATION  —  POLYMERIZATION  — 
DEPOLYMERIZATION  — CONDENSATIONS    BY    ADDITION 

§  1.  Isomerization  181 

Changes  of  Geometrical  Isomers  182 

Changes  of  Optical  Isomers  186 

Migration  of  Double  and  Triple  Bonds  190 

Decyclizations  193 

Cyclizations  and  Transformations  of  Rings  194 

Migration  of  Atoms 199 

§  2.  Polymerizations  209 

Ethylene  Hydrocarbons  210 

Acetylene  Hydrocarbons  212 

Cyclic  Hydrocarbons  216 

Aldehydes  218 

AJdolization  219 

Polyaldehydes  222 

Passage  into  Esters  .• 225 

Ketones  229 

Nitriles  and  Amides  230 

§  3.  Depolymerizations    234 

§  4.  Condensation  by  the  Addition  of  Dissimilar  Molecules  236 


CONTENTS  ix 

Aldehydes  and  Nitro-Compounds   236 

Ketones     238 

Acetylation  of  Aldehydes   240 

Hydrocarbons 241 


CHAPTER  V 
OXIDATIONS 

I.   Direct  Oxidation  with  Gaseous  Oxygen  244 

Classification  of  Direct  Oxidations  244 

Platinum  and  Related  Metals   245 

Copper     253 

Various  Metals   254 

Carbon     257 

Metallic   Oxides    258 

Metallic  Chlorides   263 

Manganese   Salts    264 

Oxidation  of  Oils  265 

Silicates     267 

II.   Oxidation  effected  by  Oxygen  Compounds   268 

Hydrogen  Peroxide   268 

Nitric   Acid    269 

Hypochlorites    270 

Chlorates     271 

Sulphur  Trioxide    272 

Permanganates    275 

Persulphates     :  276 

Nitrobenzene  277 


CHAPTER  VI 
VARIOUS   SUBSTITUTIONS   IN   MOLECULES 

§  1.  Introduction  of  Halogens  278 

Chlorination     278 

Iodine     278 

Bromine    279 

Sulphur    280 

Phosphorus     281 

Carbon     282 

Metallic   Chlorides    283 

Aluminum  Bromide    289 

Bromination     290 

Iodine     291 

Manganese     292 

Metallic  Chlorides  or  Bromides 293 

lodination     294 

§2.  Introduction  of  Sulphur   295 

§  3.  Introduction  of  Sulphur  Dioxide  297 

§4.  Introduction  of  Carbon  Monoxide   298 

§5.  Introduction  of  Metallic  Atoms   299 

Formation  of  Alcoholates  299 

Formation  of  Organo-magnesium  Complexes   300 


x  CONTENTS 

CHAPTER  VII 
Hydration 

Classification  of  Hydrations  .............................................  305 

Addition  of  Water  ....................................................  306 

Ethylene    Compounds    ................................................  306 

Acetylene   Derivatives    ................................................  308 

Nitriles  and  Imides    ..................................................  311 

Addition  of  Water  with  Decomposition,  in  Liquid  Medium  ..........  313 

Hydrolysis  of  Esters  ....................................................  313 

Use    of   Acids    ........................................................  313 

Use  of  Bases    .........................................................  318 

Hydrolysis  of  Chlorine  Derivatives  ....................................  320 

Ethers    .................................................................  321 

Acetals     ................................................................  322 

Polysaccharides     ........................................................  323 

Glucosides     .............................................................  327 

Amides  and  their  Analogs  ..............................................  331 

Addition  of  Water  with  Decomposition,  in  Gaseous  Medium  .......  337 

Hydrolysis  of  Esters    .................................................  337 

Ethers    ...............................................................  338 

Carbon  Disulphide    ...................................................  339 

Alcoholysis    ...........................................................  340 


CHAPTER 
HYDROGENATION 

Hydrogenation  in  Gaseous  System,  Generalities,  Use  of  Nickel  ........  342 

Historical     ............................................................  342 

Method  of  Sabatier  and  Senderens  ....................................  343 

Hydrogen  Generator   ..................................................  346 

Reaction  Tube    ........................  ...............................  347 

Introduction  of  the  Substance   ........................................  350 

Receiver  for  Collecting  the  Products  ..................................  355 

Hydrogenation   over  Nickel    ............................................  358 

Duration  of  the  Activity  of  the  Metal  ................................  359 

Choice  of  Reaction  Temperature  ....................................  361 

RESULTS  OF  HYDROGENATION  OVER  NICKEL  IN  GASEOUS  SYSTEM  ............  366 

Reduction  without  addition  of  hydrogen   ................................  367 

Nitrous  Oxide    ..................................................  .  .....  368 

Aromatic  Alcohols   ....................................................  369 

Phenols  and  Polyphenols  above  250°   ..................................  370 

Furfuryl   Alcohol    .....................................................  371 

Carbon  Disulphide  at  500°  .............  •  ...............................  372 

Reductions  with  Simultaneous  Addition  of  Hydrogen  ....................  373 

Oxides  of  Nitrogen   ...................................  .  ...............  374 

Aliphatic  Nitro  Derivatives  ...........................................  377 

Aromatic  Nitro  Derivatives  ...........................................  378 

Nitrous   Esters    .......................................................  382 

Oximes     ..............................................................  383 

Aliphatic  Amides   .....................................................  386 

Ethyl   Aceto-acetate    ..................................................  387 

Aromatic  Aldehydes   ..................................................  388 

Aromatic  Ketones   ....................................................  389 

Aromatic  Diketones  .  ...............................  391 


CONTENTS  xi 

Anhydrides  of  Dibasic  Acids  392 

Carbon   Monoxide    393 

Carbon  Dioxide    395 

Application  to  the  Manufacture  of  Illuminating  Gas  397 

Aromatic  Halogen  Derivatives   403 

Halogenated  Aliphatic  Acids  407 


CHAPTER   IX 
HYDROGENATION    (Continued) 

Hydrogenation  in  Gaseous  System,  Use  of  Nickel  (Continued)   408 

Addition  of  Hydrogen   408 

1.  Direct  Addition  oj  Hydrogen  to  Carbon  409 

2.  Addition  to  Hydrogen  at  Ethylene  Double  Bond 412 

Hydrocarbons    413 

Unsaturated  Alcohols   416 

Esters     417 

Ethers    418 

Unsaturated  Aldehydes    419 

Unsaturated   Ketones    420 

Unsaturated  Acids 422 

3.  Acetylene  Triple  Bond  423 

4.  Triple  Bond  between  Carbon  and  Nitrogen   426 

Aliphatic  Nitriles  427 

Aromatic   Nitriles    428 

Dicyanides     429 

5.  Quadruple  Bond  between  Carbon  and  Nitrogen  430 

Isocyanides    ." 431 

6.  Double  Bond  between  Carbon  and  Oxygen 432 

Aliphatic  Aldehydes   432 

Aromatic  Aldehydes   433 

Pyromucic   Aldehyde    434 

Aliphatic  Ketones    435 

Cyclo-aliphatic   Ketones    436 

Ketone-acids    437 

Diketones     438 

Aromatic  Ketones    441 

Quinones     442 

Ethylenic  Oxides   443 

7.  The  Aromatic  Nucleus  444 

Aromatic  Hydrocarbons    446 

Polycyclic   Hydrocarbons 452 

Aromatic  Ketones   455 

Phenols    456 

Polyphenols    460 

Phenolic   Ethers    464 

Aromatic   Alcohols    465 

Aromatic   Amines    466 

Aromatic  Acids    471 

8.  Various  Rings 472 

Trimethylene   Ring   472 

Tetramethylene    Ring    473 

Pentamethylene    Ring    474 

Hexamethylene    Ring    475 

Terpenes    477 


xii  CONTENTS 

Heptamethylene   Ring    479 

Octomethylene  Ring  480 

Naphthalene  Nucleus   481 

Anthracene   Nucleus   483 

Phenanthrene   Nucleus     484 

Pyrrol     486 

Pyridine     486 

Quinoline    488 

Carbazol    490 

Acridine    491 

9.  Carbon  Disulphide   492 

HYDROGENATION  WITH  DECOMPOSITION    493 

Hydrocarbons     493 

Alcoholic  or  Phenolic  Ethers  494 

Phenyl  Isocyanate   495 

Amines    496 

Diazo  Compounds   497 

Indol  497 


CHAPTER  X 
HYDROGENATION    (Continued) 

§  1.  Hydrogenation  in  Gaseous  System  over  Various  Metals  498 

Cobalt 499 

Ethylenic  Hydrocarbons  500 

Acetylene 501 

Benzene  and  its  Homologs  502 

Aldehydes  and  Ketones  503 

Oxides  of  Carbon  504 

Iron  : 505 

Ethylenic  Hydrocarbons  506 

Acetylene  506 

Copper  507 

Reduction  of  Carbon  Dioxide  508 

Nitro  Derivatives 509 

Nitrous  Esters  513 

Oximes 514 

Ethylenic  Compounds  515 

Acetylene  Compounds  518 

Nitriles  521 

Aldehydes  and  Ketones  522 

Platinum  524 

Combination  of  Carbon  and  Hydrogen  525 

Ethylene  Compounds  526 

Acetylene  Compounds  527 

Hydrocyanic  Acid  528 

Nitro  Derivatives  529 

Aliphatic  Aldehydes  and  Ketones 532 

Aromatic  Nucleus  534 

Polymethylene  Rings  535 

Palladium  536 

§  2.  Hydrogenation  by  Nascent  Hydrogen  in  Gaseous  System 537 

Use  of  Alcohol  Vapors  538 

Use  of  Formic  Acid  Vapors  539 

Use  of  Carbon  Monoxide  and  Water  Vapor 540 


CONTENTS  xiii 

CHAPTER  XI 
HYDROGENATION    (Continued) 

Direct  Hydrogenation  of  Liquids  in  Contact  with  Metal  Catalysts  . .  541 

Historical  542 

General  Conditions  of  the  Reaction  543 

§  1.  Method  of  Paal  544 

Use  of  Colloidal  Palladium  545 

Reduction  with  Fixation  of  Hydrogen  545 

Addition  of  Hydrogen  546 

Application  to  Alkaloids  555 

Use  of  Colloidal  Platinum  556 

§  2.  Method  of  Willstatter  562 

Method  of  Operating  562 

Use  of  Platinum  Black  562 

Nitro  Derivatives  : 564 

Ethylene  Double  Bonds  565 

Acetylene  Triple  Bonds  566 

Aldehydes  and  Ketones  567 

The  Aromatic  Nucleus  569 

Terpenes  570 

Complex  Rings  571 

Use  of  Palladium  Black  573 

Reduction  of  Carbonates  to  Formates  574 

Reduction  of  Acid  Chlorides  575 

Nitro  Derivatives  576 

Double  and  Triple  Carbon  Bonds  577 

Cyclic  Compounds  578 

Use  of  other  Metals  of  Platinum  Group 580 


CHAPTER  XII 
HYDROGENATION   (Continued) 

Direct  Hydrogenation  of  Liquids  in  Contact  with  Metal 

Catalysts    (Cont.)    584 

§  3.  Method  of  Ipatief   584 

Apparatus  Used   585 

Use  of  Nickel  585 

Formation  of  Methane   586 

Ethylene  Double  Bonds   587 

Aldehydes  and  Ketones  588 

Aromatic  Nucleus    589 

Terpenes     591 

Various  Rings   592 

Use  of  Iron  593 

Use  of  Copper  594 

Use  of  Other  Metals  595 

§  4.  Hydrogenation  of  Liquids  in  Contact  with  Nickel  under  Low 

Pressures     596 

Apparatus  of  Brochet  597 

Alleged  Activity  of  Oxides  598 

Method   of  Operating    599 

Results  Obtained   60° 

Nitro  Derivatives   60° 


xiv  CONTENTS 

Ethylene  Compounds  601 

Aldehydes  and  Ketones   602 

Various    Rings    603 

Use  of  Nascent  Hydrogen  in  Liquid  System  in  Contact  with 

Metals     604 


CHAPTER  XIII 
VARIOUS    ELIMINATIONS 

§  1.  Elimination  of  Halogens  605 

§  2.  Elimination  of  Nitrogen  606 

Diazo  Compounds  606 

Hydrazine  Derivatives  611 

§  3.  Elimination  of  Free  Carbon  613 

Decarbonization  of  Carbon  Monoxide  614 

§  4.  Elimination  of  Carbon  Monoxide  618 

Action  of  Nickel  619 

Action  of  Other  Metals  621 

§  5.  Elimination  pf  Hydrogen  Sulphide 626 

Mercaptans  626 

Thiophenols  629 

Formation  of  Thioureas  630 

§  6.  Elimination  of  Ammonia 631 

Action  of  Nickel  on  Aliphatic  Amines  631 

Phenylation  of  Aromatic  Amines 632 

Decomposition  of  Phenylhydrazones  633 

§7.  Elimination  of  Aniline    .  634 


CHAPTER  XIV 

DEHYDROGENATION 

Historical 636 

Classification  of  Dehydrogenations  638 

§  1.  Dehydrogenation  of  Hydrocarbons  639 

§  2.  Dehydrogenation  of  Hydrocyclic  Compounds  640 

Cyclohexane  Compounds    641 

Hydrides  of  Naphthalene,  Anthracene,  etc 642 

Terpenes 643 

Piperidine 647 

Action  of  Palladium  649 

§  3.  Dehydrogenation  of  Alcohols  650 

Mechanism  of  the  Decomposition  of  Alcohols 650 

Use  of  Copper  653 

Primary  Alcohols,  Preparation  of  Aldehydes  653 

Secondary  Alcohols,  Preparation  of  Ketones  659 

Use  of  Nickel  664 

Use  of  Cobalt  666 

Use  of  Iron  667 

Use  of  Platinum  668 

Use  of  Palladium  669 

Use  of  Zinc  670 

Use  of  other  Substances  671 


CONTENTS  xv 

Manganous    Oxide    672 

Stannous   Oxide    673 

Cadmium    Oxide    674 

Other  Oxides:    their  Classification   675 

Case  of  Methyl  Alcohol  676 

Carbon     679 

§4.  Dehydrogenation  of  Polyalcohols   680 

§  5.  Dehydrogenation  of  Amines   681 

Primary  Amines,  Return  to  Nitrile 681 

Secondary  and  Tertiary  Amines  682 

§  6.  Synthesis  of  Amines  683 

§  7.  Ring  Formation  by  Elimination  of  Hydrogen  684 

Use  of  Nickel  684 

Use  of  Aluminum  Chloride 685 

Use  of  Anhydrous  Oxides  686 

CHAPTER  XV 
DEHYDRATION 

Dehydration  Catalysts  687 

§  1.  Dehydration  of  Alcohols  Alone  688 

FORMATION  OF  ETHERS  ..  690 

In  Liquid  Medium  691 

In  Gaseous  System  693 

DEHYDRATION  TO  HYDROCARBONS    695 

Reaction  in  Liquid  Medium  695 

Concentrated  Mineral  Acids  696 

Zinc  Chloride  698 

Iodine  699 

Reaction  in  Gaseous  System  700 

Elements  700 

Anhydrous  Metallic  Oxides  702 

Conditions  which  Regulate  their  Action  706 

Alumina  713 

Blue  Oxide  of  Tungsten  715 

Thoria  716 

Metallic  Salts  717 

Case  of  Benzhydrol  720 

Catalytic  Passage  of  an  Alcohol  to  a  Hydrocarbon  721 

Dehydration  with  Simultaneous  Hydrogenation  722 

DEHYDRATION  OF  POLYALCOHOLS  723 

Reaction  in  Gaseous  System 726 

Ring  Formation  by  the  Dehydration  oj  Polyalcohols  727 


CHAPTER  XVI 
DEHYDRATION   (Continued) 

§2.  Dehydration  of  Alcohols  with  Hydrocarbons  728 

§  3.  Dehydration  of  Alcohols  with  Ammonia  or  Amines 729 

Reaction  in  Liquid  System   729 

Reaction  in  Gaseous  System  731 

Mixed  Amines    738 

Alkyl-piperidinea    741 

Pyrrol     742 


xvi  CONTENTS 

§4.  Dehydration  of  Alcohols  with  Hydrogen  Sulphide:    Synthesis  of 

Mercaptans     743 

Comparison  of  the  Activity  of  Various  Oxides 743 

§5.  Dehydration  of  Alcohols  with  Acids:    Esterification  747 

Catalytic  Esterification  in  Liquid  Medium  748 

Use  of  Mineral  Acids  749 

Explanation  of  their  Action  752 

The  Case  of  Glycerine  760 

Use  of  Acetanhydride    761 

Catalytic  Esterification  in  Gaseous  System  762 

Mechanism  of  the  Action  of  Oxides 763 

Case  of  Benzoic  Esters 766 

Use  of  Titania  767 

Laws  of  Esterification  over  Titania   770 

Case  of  Formic  Esters  773 

Esterification   Rates    775 

Use  of  Berylia   778 

§  6.  Dehydration  of  Alcohols  with  Aldehydes  or  Ketones  779 

Formation  of  Acetals  780 

Formation  of  Hydrocarbons   784 


CHAPTER  XVII 
DEHYDRATION    (Continued) 

§7.    Dehydration  of  Phenols  Alone   785 

Preparation  of  Simple  Phenol  Ethers   787 

Diphenylene   Oxides    787 

Mixed  Phenol  Ethers  788 

§8.    Dehydration   of   Phenols   with   Alcohols:     Synthesis    of   Alkyl 

Phenol   Ethers 789 

§  9.    Dehydration  of  Phenols  with  Amines  790 

§  10.  Dehydration  of  Phenols  with  Hydrogen  Sulphide :    Formation 

of  Thiophenols    . 791 

§  11.  Dehydration  of  Phenols  with  Aldehydes  792 

§  12.  Formation  of  Phenolic  Glucosides   793 

§  13.  Dehydration  of  Aldehydes  or  Ketones  794 

Crotonization  of  Aldehydes  Alone 795 

Crotonization  of  Ketones  Alone  797 

Crotonization  of  Aldehydes  with  Ketones  798 

Crotonization  in  Gaseous  System 801 

Dehydration  of  a  Single  Molecule   802 

Condensation  of  Aldehydes   or  Ketones  with    Various   Organic   Mole- 
cules      803 

§  14.  Dehydration  of  Aldehydes  or  Ketones  with  Ammonia 807 

§  15.  Dehydration  of  Aldehydes  with  Hydrogen  Sulphide  810 

§  16.  Dehydration  of  Amides  811 

Formation  of  Nitriles    811 

Transformation  of  Acid  Chlorides  into  Nitriles   812 

§  17.  Dehydration  of  Oximes  814 

§  18.  Direct  Sulphonation  of  Aromatic  Compounds   815 

§  19.  Condensations  by  the  Elimination  of  Alcohol  817 


CONTENTS  xvii 

CHAPTER  XVIII 
DECOMPOSITION    OF   ACIDS 

Decomposition  of  Formic  Acid  820 

Dehydrogenation    Catalysts    824 

Dehydration  Catalysts   825 

Mixed  Catalysts  826 

Decomposition  of  Monobasic  Organic  Acids  829 

Simple  Elimination  oj  Carbon  Dioxide  831 

Aliphatic  Acids  831 

Aromatic   Acids    834 

Simultaneous  Elimination  oj  Water  and  Carbon  Dioxide  837 

Preparation  of  Symmetrical  Ketones  837 

Use  of  Calcium  Carbonate  839 

Use  of  Alumina   840 

Use  of  Zinc  Oxide   841 

Use  of  Cadmium  Oxide   842 

Use  of  the  Oxides  of  Iron  843 

Use   of   Thoria    

Use  of  Manganous  Oxide  845 

Use  of  Lithium  Carbonate  846 

Formation  oj  Ketones  in  Liquid  Medium  847 

Preparation  oj  Mixed  Ketones   848 

Preparation  oj  Aldehydes  851 

Decomposition  of  Dibasic  Acids  855 

Decomposition  of  Acid  Anhydrides   857 


CHAPTER  XIX 
DECOMPOSITION   OF  THE   ESTERS   OF  ORGANIC   ACIDS 

§  1.  Esters  of  Monobasic  Acids  858 

General  Mechanism  of  this  Catalysis  859 

Case  of  Alumina   860 

Case  of  Thoria  861 

Case  of  Titania 863 

Case  of  Benzoic  Esters  864 

Formic  Esters   866 

§  2.  Decomposition  of  Esters  with  Ammonia  871 

§  3.  Esters  of  Dibasic  Acids  872 

CHAPTER  XX 

ELIMINATION    OF   HALOGEN   ACIDS   OR  SIMILAR 
MOLECULES 

§  1.  Separation  of  the  Acid  from  a  Single  Molecule  876 

Use  of  Anhydrous  Metallic  Chlorides 876 

Mechanism  of  this  Catalysis  878 

Use  of  Oxides  or  Metals  881 

§2.  Molecular  Condensations  by  the  Elimination  of  a  Halogen  Acid  883 

Alkylation  oj  Aromatic  Molecules  884 

Method  of  Operating  884 

Reversal  of  the  Reaction  887 

Results  Obtained  .  889 


xviii  CONTENTS 

Synthesis  of  Ketones   891 

Method  of  Operating  892 

Results    Obtained    893 

Formation  oj  Amides   895 

Ring  Formation   896 

Mechanism  oj  the  Reaction  898 

Chlorides  that  may  be  Substituted  for  Aluminum  Chloride  899 

Formation  oj  Aromatic  Amines  by  Hojmann's  Reaction  901 

Condensations  in  the  Aliphatic  Series   902 

§  3.  Separation  of  Alkaline  Chloride,  Bromide  or  Iodide  904 


CHAPTER  XXI 

DECOMPOSITION   AND    CONDENSATION    OF 
HYDROCARBONS 

Action  of  Heat  on  Hydrocarbons  905 

Cracking  906 

Case  of  Benzene  907 

Case  of  Petroleum  908 

Case  of  Solvent  Naphtha  909 

Action  of  Catalysts  910 

Paraffine  Hydrocarbons 911 

Ethylene  Hydrocarbons 912 

Acetylene  Hydrocarbons,  Acetylene  913 

First  Kind  of  Reaction  914 

Second  Kind  of  Reaction  916 

Superposition  of  the  Two  Kinds  917 

Cyclic  Hydrocarbons  921 

Terpenes  922 

Reactions  carried  out  in  the  Presence  of  Hydrogen  924 

Case  of  Acetylene  925 

Synthesis  of  Petroleums  926 

Theory  of  the  Origin  of  Petroleum  928 

Action  of  Anhydrous  Aluminum  Chloride  929 

Applications  to  the  Treatment  of  Petroleum  932 

Use  of  Finely  Divided  Metals  932 

Use  of  Oxides  934 

Use  of  Anhydrous  Chlorides  935 


APPENDIX  TO  CHAPTERS  XI  AND  XII 
HYDROGENATION    OF   LIQUID   FATS 

Nature  of  Liquid  Fats  937 

Iodine    Number    938 

History  of  Hydrogenation   939 

Catalysts     941 

Nickel    941 

Use  of  the  Oxides  and  Salts  of  Nickel 943 

Palladium    946 

Life  of  Catalysts   947 

Neutralization  of  Oils   948 

Troubles  with  Moisture 949 

Amount  of  Catalysts  951 


CONTENTS  xix 

Temperature     952 

Hydrogen    953 

Process  of  Bergius  954 

Volume   of  Hydrogen   Required    955 

Apparatus     957 

Apparatus   of   Erdmann    958 

Apparatus  of  Schwoerer   959 

Apparatus  of  Schlinck   960 

Apparatus  of  Wilbuschewitch   961 

Apparatus   of   Ellis    962 

Apparatus  of  Kayser   963 

Apparatus   of    Woltman    964 

Results 965 

Physical  Constants  of  Hardened  Oils  966 


PERIODICALS  CITED  AND  THEIR  ABBREVIATIONS 

Am.  Chem.  J.    American  Chemical  Journal,  Baltimore. 

Annalen.    Annalen  der  Chemie  und  Pharmacie  (Liebig's),  Leipzig. 

Ann.  Chim.  Phys.    Annales  de  chimie  et  de  physique,  Paris. 

Arch.  Pharm.    Archiv  der  Pharmacie,  Berlin. 

Berichte    Berichte  der  deutschen  chemischen  Gesellschaft,  Berlin. 

Bull.  Soc.  Chim.    Bulletin  de  la  Societe  chimique,  Paris. 

Caoutchouc  et  G.    Caoutchouc  et  gutta-percha,  Paris. 

C.  A.    Chemical  Abstracts,  Columbus. 

C.  or  Chem.  Centr.    Chemisches  Centralblatt,  Leipzig. 

Chem.  News    Chemical  News  (The),  London. 

Chem.  Week.    Chemisch  Weekblad,  Amsterdam. 

Chem.  Zeit.    Chemiker  Zeilung,  Cothen. 

Compt.  rend.     Comptes  Rendus  des  Seances   de  I'Academie   des  Sciences   de 

Paris,  Paris. 

Dinglers    Dinglers  Polytechnischer  Journal,  Stuttgart. 
Gas  Light.    Gas  Lighting,  London. 
Gaz.  Chim.  Ital.    Gazetta  chimica  italiana,  Palermo. 
Gaz    Le  Gaz,  Paris. 
Jahresb.    Jahresberichte   uber  die  Fortschritte   der  physischen   Wissenschaften 

(von  J.  Berzelius),  Tubingen. 

J.  Am.  Chem  Soc.    Journal  oj  the  American  Chemical  Society,  Easton. 
J.  Chem.  Ind.  Tokio    Journal  oj  Chemical  Industry  oj  Japan,  Tokio. 
J.  Ind.  Eng.  Chem.    Journal  oj  Industrial  and  Engineering  Chemistry,  New  York. 
J.  Chem.  Soc.    Journal  oj  the  Chemical  Society,  London. 
J.  Gas  Light.    Journal  oj  Gas  Lighting,  London. 
Jour.  Off.    Journal  officiel  de  la  Republique  Franqaise,  Paris. 
J.  Pharm.  Chim.    Journal  de  Pharmacie  et  de  Chimie,  Paris. 
J.  Phys.  Chem.    Journal  oj  Physical  Chemistry,  Ithaca. 
J.  prakt.  Chem.    Journal  fur  praktische  Chemie,  Leipzig. 
J.  Russ.  Phys.  Chem.  Soc.    Journal  of  the  Russian  Physico-Chemical  Society, 

Petrograd. 

J.  Soc.  Chem.  Ind.    Journal  of  the  Society  of  Chemical  Industry,  London. 
Lincei    Atti  della  Reale  accademia  dei  Lincei,  Rome. 
Mat.  grasses    Matieres  grasses,  Paris. 
Monatsh.    Monatshefte  fur  Chemie,  Vienna. 
Nachr.  Ges.  der  Wiss.  Gottingen    Nachrichten  der  koniglichen  Gesellschafft  der 

Wissenschaften,  Gottingen. 
Phil.  Mag.    Philosophical  Magazine,  London. 
Proc.  Roy.  Soc.    Proceedings  of  the  Royal  Society,  London. 
Pogg.  Ann.    Annalen  der  Physik  und  Chemie  (Poggendorf),  Leipzig. 
Quart.  J.  Science    American  Journal  of  Science,  New  Haven. 
Rec.   Trav.   Chim.   Pays-Baa    Recueil   des    travaux    chimiques   des   Pays-Bos, 

Leyden. 

Rev.  Mois.    Revue  du  Mois,  Paris. 
Rev.  gen  de  chim.  pure  et  app.    Revue  generate  de  chimie  pure  et  appUquee, 

Paris. 

Rev.  Sci.    Revue  Scientifique,  Paris. 
Sitz.   Akad.    Wien.    Sitzungsberichte    der   mathematisch-naturwissenschaftUchen 

Klasse  der  kaiserlichen  Akademie  der  Wissenschaften,  Vienna. 

xxi 


xxii      PERIODICALS  CITED  AND  THEIR  ABBREVIATIONS 

Seif.  Zeit.    Seijensieder  Zeitung. 

Soc.  Tech.  Gaz.    Societe  technique  de  ^Industrie  gaziere,  Paris. 

Soc.  Esp.  Quim.    Anales  de  la  societad  espanola  de  fisica  y  quimica,  Madrid. 

Trans.  Far.  Soc.    Transactions  of  the  Faraday  Society,  London. 

Zeit.  anorg.  Chem.    Zeitschrijt  fur  anorganische  Chemie,  Hamburg. 

Zeit.   f.   Chem.     Kritische   Zeitschrijt   jur   Chemie,   Physik    und   Mathematik 

(Kekule),  Heidelberg  and  Gottingen. 
Zeit.  Elektroch.    Zeitschrijt  jur  Elektrochemie,  Halle. 
Z.  phys.  Chem.    Zeitschrijt  jur  physikalische  Chemie,  Leipzig. 


INTRODUCTION 

PAUL   SABATIER 

PAUL  SABATIER  was  born  at  Carcassonne  Nov.  5,  1854.  Admitted 
at  the  same  time  to  the  Polytechnic  and  the  Normal  School  in  1874, 
he  chose  the  latter  from  which  he  went  out  in  1877  receiving  the 
highest  grade  in  the  competitive  examination  for  agregation  de  phy- 
sique.1 After  spending  a  year  as  Professor  at  the  Lycee  of  Nimes, 
he  became,  in  October,  1878,  assistant  to  Berthelot  at  the  College  de 
France.  In  July,  1880,  he  received  the  degree  of  Doctor  of  Science, 
his  thesis  being  on  Metallic  Sulphides.  After  having  been  Maitre  de 
Conference  in  physics  in  the  Faculty  of  Sciences  at  Bordeaux  for  more 
than  a  year,  he  took  charge,  in  January,  1882,  of  the  course  in  physics 
in  the  Faculty  of  Sciences  of  Toulouse  which  he  was  never  to  leave. 
Taking  charge  of  the  chemistry  course  at  the  end  of  1883,  he  was 
made  Professor  of  Chemistry  November  24,  1884,  a  position  which 
he  still  occupies. 

His  chemical  investigations  are  very  numerous  and  touch  various 
branches  of  that  science:  most  of  them  have  been  published  in  the 
Comptes  Rendus  de  I'Academie  des  Sciences,  the  Bulletin  de  la  So- 
ciete  Chimique,  and  the  Annales  de  Chimie  et  de  Phisique. 

His  researches  in  physical  chemistry  stretch  from  1879  to  1897 
and  comprise  numerous  thermochemical  measurements  (sulphides 
1879-1881,  chlorides  1889,  chromates  1886,  copper  compounds  1896- 
1897,  etc.),  a  thorough  study  of  the  velocity  of  transformation  of 
metaphosphoric  acid  (1887-1889),  studies  on  absorption  spectra 
(1886  and  1894),  on  the  partition  of  a  base  between  two  acids 
(1886-1887),  etc. 

In  inorganic  chemistry  he  has  published  numerous  articles  on 
metallic  sulphides  (1879-1880),  the  sulphides  of  boron  and  silicon 
(1880-1891),  hydrogen  disulphide  (1886),  the  selenides  of  boron  and 
silicon  (1891),  metallic  chlorides  (1881,  1894-1895),  the  chlorides 
(1881,  1888)  and  the  bromide  of  copper  (1896).  A  profound  study 
of  the  oxides  of  nitrogen,  which  led  to  the  characterization  of  metallic 
nitrides,  was  carried  out  (1897-1896)  with  the  assistance  of  his  pupil, 

1  The  agregation  is  a  competitive  examination  which  is  considered  extremely 
difficult. 


xxiv  INTRODUCTION 

J.  B.  Senderens.  He  prepared  the  deep  blue  nitrosodisulphonic  acid 
(1896-1897),  defined  the  tetracupric  salts  (1897),  and  obtained  the 
basic  mixed  argento-cupric  salts  (1897-1899)  which  formed  the  start- 
ing point  for  a  whole  series  of  analogous  compounds  which  Mailhe 
prepared  subsequently. 

His  investigations  in  organic  chemistry  (starting  in  1897)  are  the 
most  important  and  include  the  general  method  of  catalytic  hydro- 
genation  in  contact  with  finely  divided  metals,  which  was  awarded 
the  Nobel  prize  for  chemistry  in  1912.  The  experiments  involved 
in  this  as  well  as  in  the  inverse  dehydrogenation,  were  carried  out 
with  the  aid  of  his  successive  pupils,  J.  B.  Senderens  (1899-1905), 
Alfonse  Mailhe  (1906-1919),  Marcel  Murat  (1912-1914),  Leo  Espil 
(1914)  and  Georges  Gaudion  (1918-1919). 

The  study  of  metallic  oxides  as  catalysts  led  Sabatier  with  Mailhe 
to  discover  a  whole  series  of  methods  of  transforming  alcohols  and 
phenols  into  mercaptans,  amines,  ethers,  esters,  etc.,  and  also  trans- 
forming acids  (1906-1914).  At  the  same  time  he  carried  out,  either 
with  Mailhe  or  Murat,  a  large  number  of  syntheses  of  hydrocarbons 
and  alcohols  of  the  cyclohexane  series,  etc.  (1904-1915). 

In  agricultural  chemistry,  Sabatier  has  published  about  fifteen 
memoirs  on  various  subjects  as  well  as  Lessons  on  Agricultural 
Chemistry. 

The  Academy  of  Sciences  of  Paris  awarded  him  the  Lacaze  prize 
in  1897  and  the  Jecker  prize  in  1905  and  elected  him  correspondent 
of  the  chemical  section  in  1901,  then  non-resident  membre  titulaire  in 
April,  1913.  Awarded  the  Nobel  Prize  in  Chemistry  in  1912,  Sa- 
batier received  in  1915  the  Davy  Medal  of  the  Royal  Society  of 
London  of  which  he  was  elected  a  foreign  member  in  1918.  He  is 
also  a  foreign  member  of  the  Royal  Institution,  the  Academy  of 
Sciences  of  Amsterdam,  the  Academy  of  Sciences  of  Madrid,  the 
Royal  Society  of  Bohemia,  etc. 

Profoundly  attached  to  Toulouse,  where  he  belonged  to  various 
local  academies,  Sabatier  refused  to  leave  his  University  to  occupy 
the  chair  at  the  Sorbonne  left  vacant  in  1907  by  the  death  of  Moissan. 
Dean  of  the  Faculty  of  Sciences  since  1905,  he  has  created  the  three 
technical  Institutes  of  Agriculture,  of  Chemistry  and  of  Electro- 
technique  which  are  thronged  by  a  large  number  of  students. 


Of 

CAUFGRMI; 


CATALYSIS 
IN  ORGANIC  CHEMISTRY 

CHAPTER   I 
CATALYSIS    IN    GENERAL 

1.  BY  catalysis  we  designate  the  mechanism  by  virtue  of  which 
certain  chemical  reactions  are  caused,  or  accelerated,  by  substances 
which  do  not  appear  to  take  any  part  in  the  reactions. 

A  mixture  of  hydrogen  and  oxygen  is  stable  at  ordinary  tempera- 
tures, but  the  introduction  of  a  piece  of  platinum  black  causes  im- 
mediate explosive  combination;  the  platinum  black  is  not  visibly 
affected  and  can  repeat  the  same  effects  indefinitely. 

2.  Hydrogen  peroxide  decomposes  very  slowly  in  cold  water  solu- 
tion, a  30  volume  solution  requiring  more  than  240  hours  at  17°  for 
50%  decomposition,  but  the  addition  of  0.06  g.  platinum  black  to 
20  cc.  of  such  a  solution  causes  a  vigorous  evolution  of  oxygen  and 
reduces  the  period  of  half  decomposition  to  8  seconds  at  14°. x     The 
platinum  black,  which  does  not  seem  to  be  altered,  has  by  its  presence 
enormously   accelerated   the   reaction   which   normally   takes   place 
spontaneously  but  very  slowly. 

3.  Substances  which  provoke  or  accelerate  reactions  without  them- 
selves being  altered  are  called  catalysts. 

4.  History  of  Catalysis.     The  first  scientific  observation  of  a 
catalytic  transformation  appears  to  be  due  to  Kirchhof, 2  who,  in 
1811,  showed  thatjnineral  acids,  in  hot  water  solution,  change  starch 
into  dextrine  and  sugar,  without  being  themselves  altered  by  the 
reaction. 

A  short  time  afterwards,  in  1817,  Sir  Humphrey  Davy 8  observed 
that  a  slightly  heated  platinum  spiral  introduced  into  a  mixture  of 
air  and  a  combustible  gas,  hydrogen,  carbon  monoxide,  or  hydro- 
cyanic acid,  becomes  incandescent  and  causes  the  slow  oxidation  of 

1  LEMOINE,  Compt.  rend.,  162,  657  (1916). 

2  KIBCHHOF,  Schweigger's  Jour.  4,  108  (1812). 

3  DAVY,  H.,  Phil.  Trans.,  97,  45  (1817). 


6    .  CATALYSIS  IN  ORGANIC  CHEMISTRY  '  2 

the  gas.  In  1820  Edmond  Davy4  discovered  that  platinum  black 
Itan;  ignite  Alcohol  with  which  it  is  wetted.  Platinum  sponge  also 
possesses  this  power  of  provoking  reactions  without  undergoing  any 
appreciable  change,  and  in  1831,  Pelegrin  Phillips,5  a  vinegar  manu- 
facturer of  Bristol,  took  out  an  English  patent  on  the  use  of  plati- 
num sponge  to  oxidise  by  air  the  sulphur  dioxide  obtained  by  roast- 
ing pyrites,  thus  producing  sulphur  trioxide.  This  was  the  germ  of  the 
contact  process  for  the  manufacture  of  sulphuric  acid,  which  required 
the  labors  of  half  a  century  to  render  it  industrially  practicable. 

In  his  masterful  Treatise  on  Chemistry,  Berzelius 6  discussed 
phenomena  of  this  kind  in  which  the  presence  of  a  material  apparently 
having  nothing  to  do  with  a  reaction  can  yet  cause  that  reaction  to 
take  place.  Adopting  a  term  which  had  been,  used  in  the  seventeenth 
century  by  Libavius 7  with  a  different  meaning,  he  grouped  these 
phenomena  under  the  designation  catalytic,  from  the  Greek  Ka.raj 
down,  and  Avc^  loose,  I  unloose. 

5.  Diversity  in  Catalysis.     The  reactions  in  which  catalysis  is 
observed  have  multiplied  with  the  advance  of  chemistry.    They  are 
extremely  varied  but  can  be  divided  into  two  distinct  groups. 

6.  First  we  have  catalysis  in  a  homogeneous  system,  that  is,  where 
there  is  an  intimate  mixing  of  the  various  constituents,  or  at  least 
between  one  of  them  and  the  catalyst  that  causes  or  accelerates  the 
reaction.    This  is  the  case  with  the  soluble  ferments  which  are  not 
considered  in  this  treatise;  it  is  also  the  case  with  water  vapor  in 
gaseous  mixtures;  with  iodine,  sulphur  and  various  metal  chlorides 
employed  to  aid  chlorinations ;  with  mineral  acids  in  aldolization  or 
crotonization  as  well  as  in  the  formation  or  saponification  of  esters; 
with  alkalies  in  saponification;  with  ferrous  or  manganous  salts  in 
oxidations;  with  zinc  chloride  in  the  dehydration  of  alcohol;  with 
mercurous  sulphate  in  the  sulphonation  of  aromatic  compounds;  with 
anhydrous  ether  in  the  preparation  of  organo-magnesium  complexes; 
and  even  doubtless,  in  the  Friedel  and  Crafts  reaction  with  aluminum 
chloride  which  is  partially  soluble  in  the  liquids  used. 

7.  The  second  group  is  that  of  heterogeneous  systems  in  which,  for 
example,  a  solid  catalyst  is  brought  into  contact  with  gaseous  or  liquid 
systems  capable  of  reacting.    It  acts  only  by  its  surface,  if  it  is  com- 
pact and  remains  so  during  the  reaction;  by  all  its  mass  if  it  is 

*  DAVY,  E.,  Schweigger's  Jour.  34,  91  (1822);  38,  321  (1823). 
«  English  patent  6,069  of  1831. 

6  BERZELIUS,  Traite  de  Chemie,  I,  110  (1845). 

7  LIBAVIUS,  Alchemia,  Lib.  II,  vol.  I,  chapters  XXXIX  and  XL,  Frankfort, 
1611. 


3  CATALYSIS  IN  GENERAL  10 

porous,  its  surface  then  being  extremely  large  as  compared  with  its 
weight.  The  influence  of  the  almost  indefinite  extension  of  the  sur- 
face in  the  finely  divided  state  is  such  that  we  are  tempted  to  think 
of  the  catalytic  activity  of  a  material  as  belonging  exclusively  to 
that  state  (130). 

8.  Autocatalysis.     Ostwald   has   designated   by   this  term  those 
reactions  in  which  the  products  of  the  reactions  accelerate  the  re- 
actions. 

Thus  hydrogen  and  oxygen,  rigorously  dried,  do  not  combine  even 
at  1000°,  but  if  the  combination  is  once  started,  the  water  vapor  so 
formed  greatly  favors  the  reaction,  rendering  it  excessively  rapid  and 
explosive. 

The  decomposition  of  hydrogen  selenide,8  of  arsine*  and  of 
stibine 10  are  cases  of  autocatalysis,  since  the  selenium,  arsenic,  and 
antimony  set  free  accelerate  the  reactions  when  once  they  are  started. 

Pure  nitric  acid  acts  only  slowly  on  many  pure  metals,  silver,  cop- 
per, bismuth,  cadmium,  and  mercury,  but  when  once  started,  the 
reaction  accelerates  itself  because  nitrous  fumes  are  produced  which 
facilitate  the  attack  so  that  the  reaction  may  become  violent.11 

We  find  further  examples  of  autocatalysis  in  the  spontaneous 
changes  which  certain  organic  nitro  compounds  undergo,  e.  g.  powders 
with  nitrocellulose  as  a  base,  such  as  powder  B ; 12  these  changes 
produce  acid  vapors  which  accelerate  the  decomposition. 

9.  Negative   Catalysts.    Certain  materials,  when  present  in  a 
chemical  system,  exercise  an  unfavorable  or  retarding  influence;  such 
are  negative  catalysts,  the  presence  of  which  increases  rather  than  de- 
creases the  chemical  friction  and  may  sometimes  even  paralyze  the 
normal  play  of  affinities. 

10.  For  the  present,  it  is  convenient  to  place  in  this  class  sub- 
stances capable  of  altering  positive  catalysts  so  as  to  diminish  their 
efficient  action. 

As  early  as  1824,  Turner13  observed  that  traces  of  various  sub- 
stances suppressed  the  catalytic  activity  of  finely  divided  platinum 
and  mentioned  as  such  ammonium  sulphide,  carbon  disulphide,  and 
hydrogen  sulphide. 

8  BODENSTEIN,  Zeit.  physik.  Chem.,  29,  428  (1899). 

9  COHEN,  Zeit.  physik.  Chem.,  20,  303  (1896). 

10  STOCK  and  GUTTMANN,  Berichte,  37,  901  (1904).  BODENSTEIN,  Ibid,  p.  1361. 

11  VELEY,  Jour.  Soc.  Chem.  Ind.,  10,  204  (1891). 

12  The  French  cannon  powder  which  was  used  during  the  World  War.    It 
is  pure  nitrocellulose  gelatinized  by  a  mixture  of  2  parts  ether  to  1  part  alcohol. 

18  TURNER,  Pogg.  Ann.,  2,  210  (1824). 


11  CATALYSIS  IN  ORGANIC  CHEMISTRY  4 

In  the  manufacture  of  sulphuric  acid  by  the  contact  process  the 
presence  of  vapors  of  mercury,  phosphorus,  and  particularly  arsenic 
in  the  gas  is  sufficient  to  impair  rapidly  and  destroy  ultimately  the 
catalytic  action  of  the  platinized  asbestos. 

In  the  use  of  finely  divided  nickel  as  a  catalyst  for  direct  hydro- 
genation,  traces  of  chlorine,  bromine,  iodine,  or  sulphur  compounds 
in  the  metal,  in  the  hydrogen,  or  in  the  substance  to  be  treated,  suf- 
fice to  prevent  the  reaction  completely  and  somehow  act  as  veritable 
poisons  for  the  mineral  ferment.14 

Many  other  substances,  without  being  toxic  to  the  nickel,  which 
they  do  not  seem  to  injure,  can  retard  the  hydrogenation  by  their 
presence,  e.  g.  glycerine,  various  organic  acids,  etc.  Examples  will 
be  given  in  Chapter  II  (112  et  seq.).  In  hydrogenations  with  nickel, 
the  presence  of  small  amounts  of  carbon  monoxide  in  the  hydrogen 
exercises  a  marked  retarding  influence.15 16 

11.  Negative  catalysts,  which  by  their  presence,  stabilize  a  chem- 
ical system  and  render  its  transformation  more  difficult,  have  been 
less  studied  than  positive,  but  numerous  examples  may  be  given.  It 
has  long  been  known  that  hydrogen  peroxide  keeps  better  when 
slightly  acid.  The  addition  of  a  few  hundredths  of  one  per  cent  of 
sulphuric  or  hydrochloric  acid  to  a  30  volume  hydrogen  peroxide 
considerably  augments  its  stability.  Thus  at  65°,  pure  hydrogen 
peroxide  required  3.2  hours  for  50  per  cent  decomposition  but  this 
was  increased  to  35  hours  by  the  addition  of  0.026  molecule  of  hydro- 
chloric acid.1T 

The  spontaneous  oxidation  of  chloroform  to  carbonyl  chloride  is 
hindered  by  the  presence  of  a  little  alcohol. 

Hydrocyanic  acid  is  stabilized  by  traces  of  hydrochloric  or  sul- 
phuric acid.18 

In  the  oxidation  of  phenols  by  hydrogen  peroxide  in  the  presence 
of  ferric  chloride  as  catalyst,  the  reaction  is  retarded  by  the  presence 
of  mineral  acids  and  even  more  by  acetic,  oxalic,  and  citric  acids.19 

The  formation  of  the  organo-magnesium  halides  in  the  Grignard 
reaction  is  retarded  by  the  presence  of  anisol,  ethyl  acetate,  chloro- 
form or  carbon  disulphide  (303). 

14  SABATIER,  Berichte,  44,  1984  (1911). 

15  MAXTED,  Chem.  News,  117,  73  (1918). 

16  Numerous  quantitative  experiments  made  by  the  translator  in  the  Lab- 
oratory of  Colgate  and  Company  showed  that  catalytic  nickel  for  hydrogenation 
is  more  injured,  in  use,  by  carbon  monoxide  than  by  any  other  catalyzer  poison 
that  is  apt  to  be  present.  —  E.  E.  R. 

17  LEMOINE,  Compt.  rend.,  161,  47  (1915). 

18  LDSBIG,  Annalen,  18,  70  (1836). 

19  COLIN  and  SENECHAL,  Compt.  rend.,  153,  76  (1911). 


5  CATALYSIS  IN  GENERAL  13 

In  the  abstraction  of  halogens  in  the  Wurtz  or  Fittig  synthesis  of 
hydrocarbons,  benzene  and  petroleum  ether  exercise  an  unfavorable 
influence  (605). 

In  the  very  complex  reaction  of  the  vulcanization  of  rubber,  in 
which  a  large  number  of  substances  have  a  beneficial  effect  (104  and 
107),  phenyl-hydrazine  is  a  very  marked  negative  catalyst.20 

12.  Water  which  so  often  acts  as  a  positive  catalyst,  can  some- 
times retard  or  even  prevent  reactions. 

Moist  hydrogen  reduces  nickel  oxide  less  rapidly  than  dry.21 

The  decomposition  of  oxalic  acid  by  hot  concentrated  sulphuric 
acid  is  impeded  by  the  addition  of  very  small  amounts  of  water.  The 
time  of  decomposition,  under  the  same  conditions  of  heating,  is  more 
than  trebled  by  the  addition  of  0.05%  of  water,  while  1%  of  sulphur 
trioxide  renders  the  reaction  tumultuous.22 

The  presence  of  a  little  water  retards  the  decomposition  of  diazo- 
acetic  ester  in  alcoholic  solution.23 

Moisture  retards  the  fixation  of  oxygen  in  the  direct  oxidation  of 
unsaturated  organic  compounds  in  the  presence  of  metallic  catalysts.24 

The  presence  of  traces  of  water  hinders  the  attack  on  metallic 
aluminum  by  fatty  acids  and  by  methyl,  butyl,  amyl,  and  benzyl 
alcohols  as  well  as  by  various  monophenols,  ordinary  phenol,  the 
cresoles  and  a-  and  ^g-naphthols.25 

13.  In  chemical  systems  in  which  autocatalysis  takes  place  (8), 
the  presence  of  substances  which  form  stable  compounds  with  the 
catalysts  engendered  during  the  reaction,  hinders  their  effect.    Hence 
such  substances  are  stabilizers,  or  negative  catalysts. 

In  the  action  of  nitric  acid  on  metals,  various  oxidising  agents, 
hydrogen  peroxide,  potassium  permanganate,  and  chloric  acid  are 
negative  catalysts  because  they  hinder  the  accumulation  of  nitrous 
fumes  by  oxidising  them  to  nitric  acid  and  thus  preventing  their  ac- 
tion as  positive  catalysts. 

With  regard  to  powders  having  organic  nitrates  as  bases  (powder 
B,  nitrogylcerine,  etc.),  all  substances,  such  as  amyl  alcohol  and 
diphenylamine,  which  are  capable  of  fixing,  either  as  salts  or  as 
esters,  the  acid  products  engendered  by  the  slow  spontaneous  denitri- 
fication  of  such  powders  and  which  hasten  their  decomposition,  are 
stabilizers. 

20  PEACHEY,  Jour.  Soc.  Chem.  Ind.,  36,  424  (1917). 

21  SABATIER  and  ESPIL,  Compt.  rend.,  158,  668  (1914). 

22  BREDIG  and  FRABNKEL,  Berichte,  39,  1756  (1906). 

28  MILLAR,  Zeit.  physik.  Chem.,  85,  129  (1913).  BRAUNE,  Ibid.,  p.  170. 
SNETHLAGE,  Ibid.,  p.  211. 

2*  FOBJN,  Zeit.  anorg.  Chem.,  22,  1451  (1909). 

28  SELIGMAN  and  WILLIAMS,  J.  Soc.  Chem.  Ind.,  37,  159  (1918). 


14  CATALYSIS  IN  ORGANIC  CHEMISTRY  6 

14.  Inversion  of  Reactions.    According  to  circumstances,  cat- 
alysts are  frequently  able  to  work  in  inverse  directions. 

We  have  seen  above  (2)  that  platinum  black  thrown  into  hydro- 
gen peroxide,  induces  its  rapid  decomposition  with  separation  of 
oxygen.  Inversely,  platinum  black  serves  to  oxidise  many  substances, 
for  example,  alcohol  which  it  transforms  into  aldehyde  and  acetic 
acid  (244).  It  is  now  an  oxidation  catalyst  and  now  a  deoxidation 
catalyst. 

15.  At  about  350°,  hydrogen  and  iodine  vapor  combine  rapidly  in 
contact  with  platinum  sponge,26  and  at  the  same  temperature  and 
with  the  same  catalyst,  hydrogen  iodide  is  dissociated.27 

Finely  divided  metals  such  as  nickel  reduced  from  the  oxide, 
readily  add  hydrogen  to  hydrogenizable  substances  at  180°;  benzene 
is  thus  transformed  into  cyclohexane  (446).  On  the  contrary,  the 
inverse  effect  is  produced  when  cyclohexane  vapor  is  passed  over 
nickel  at  300°;  hydrogen  is  eliminated  and  benzene  is  regenerated 
(641). 

Reduced  copper  which  is  capable  of  hydrogenating  aldehydes  to 
alcohols  at  180°  (522),  dehydrogenates  alcohols  at  250°  to  produce 
aldehydes  (653). 

The  direct  hydrogenation  of  nitriles  over  nickel  at  180°  readily 
furnishes  primary  amines  (426) ;  but  inversely,  nickel  causes  the  de- 
composition of  the  amines  at  350°  into  the  nitriles  and  hydrogen 
(681). 

Platinum,  nickel,  and  copper  are  thus  catalysts  of  hydrogenation 
or  of  dehydrogenation  as  the  case  may  be. 

16.  Phenol  vapor  passed  over  thoria  at  450°,  is  regularly  dehy- 
drated to  form  phenyl  oxide   (786) ;  but  the  same  catalyst  at  the 
same  temperature  can  bring  about  the  splitting  of  phenyl  oxide  by 
water  to  regenerate  phenol.28    Hence  thoria  is  at  the  same  time  a 
catalyst  for  hydration  and  for  dehydration. 

17.  It  is  the  same  way  with  strong  mineral  acids,  such  as  sulphuric 
and  hydrochloric,  which  are  equally  capable  of  bringing  about  the 
addition  of  water  as  in  the  saponification  of  esters    (313),  or  its 
elimination  as  in  esterification  (749). 

18.  Soluble  ferments,  such  as  emulsine,  which  are  in  reality  true 
catalysts,  acting  in  homogeneous  system,  easily  decompose   gluco- 
sides  by  hydration  and  are  also  capable  of  synthesizing  glucosides 
by  dehydration.    Thus  galactose  treated  with  emulsine  in  concen- 

2«  CORENWINDER,  Ann.  Chim.  Phys.  (3),  34,  77  (1852). 

27  HAUTEFEUILLE,  Compt.  rend.,  64,  608  (1867). 

28  SABATIER,  and  ESPIL,  Bull  Soc.  Chim.,  (4),  15,  228  (1914). 


7  CATALYSIS  IN  GENERAL  24 

trated  solution  condenses  by  dehydration  into  galactobiose;  the 
latter,  on  the  contrary,  in  dilute  solution,  is  hydrated  by  the  emulsine 
to  regenerate  the  galactose.29 

19.  Reversible  Reactions.    In  any  reaction  in  which  catalysts 
are  able  to  activate  the  transformation  in  the  two  opposite  directions, 
there  results  an  equilibrium,  the  same  limit  being  reached  from  either 
end.    The  catalyst  only  modifies  the  velocity  of  the  opposing  re- 
actions without  essentially   changing  their   character;   consequently 
in  reversible  reactions,  the  location  of  the  limit  is  not,  in  general, 
changed  by  the  intervention  of  the  catalyst,  though  the  catalyst 
enormously  shortens  the  time  required  to  reach  that  limit. 

20.  Lemoine     has     verified     this     for     hydriodic     acid     which 
immediately  reaches  its  limit  of  decomposition,  19%  at  350°,  in  the 
presence  of  platinum  sponge.    Without  a  catalyst,  at  the  same  tem- 
perature, under  2  atmospheres  pressure,  the  limit  was  18.6%  but  was 
not  reached  till  after  250  to  300  hours.30 

21.  Berthelot  arrived  at  the  same  conclusions  with  the  esterifica- 
tion  of  alcohols  by  acetic  acid.    For  equivalent  amounts  of  ethyl 
alcohol   and   acetic   acid,  the  limit  of  66.6%    esterification   is   not 
attained  at  room  temperature  till  after  the  lapse  of  several  years  of 
contact:    on  the  contrary,  in  the  presence  of  traces  of  hydrochloric 
or  sulphuric  acids,  the  identical  limit  is  reached  in  a  few  hours. 

22.  An  immediate  consequence  of  the  foregoing  is  that,  in  rever- 
sible reactions,  the  location  of  the  limit  is  independent  of  the  nature 
of  the   catalyst.    This  has  been  verified   for  the   condensation  of 
acetaldehyde.    Whatever  causes  its  polymerization  into  paraldehyde 
(hydrochloric  acid,  sulphur  dioxide,  oxalic  acid,  or  zinc  sulphate, 
etc.)   always  transforms  the  same  proportion.81 

23.  Velocity  of  Catalyzed  Reactions.     The  presence  of  a  cat- 
alyst greatly  influences  the  velocity  of  reactions.     It  is  in  order  to 
examine  the  effect  of: 

1.  Temperature, 

2.  Pressure, 

3.  Quantity  of  catalyst. 

24.  Temperature.    Temperature  plays  a  capital  role  in  many 
catalytic  reactions,  just  as  it  does  in  most  chemical  changes.    They 
do  not  take  place  except  above  a  certain  temperature;  the  direct 
hydrogenation  of  benzene  in  the  presence  of  nickel  hardly  takes  place 

29  BOURQUELOT  and  AUBRY,  Compt.  rend.,  163,  60  (1916). 

80  LEMOINE,  Ann.  Chim.  Phys.  (5),  12,  145  (1877). 

81  TURBABA,  Zeit.  physik.  Chem.,  38,  505  (1901). 


25  CATALYSIS  IN  ORGANIC  CHEMISTRY  8 

at  all  below  70°,  while  that  of  ethylene  begins  as  low  as  30°  (413), 
and  that  of  acetylene  goes  on  at  room  temperature  (423). 

The  decomposition  of  alcohol  into  ethylene  and  water  by  blue 
oxide  of  tungsten  commences  only  at  about  250°  (709)  ;  the  dehydra- 
tion of  phenol  to  phenyl  oxide  by  thoria  requires  a  temperature  above 
400°  (786). 

25.  Elevation    of    the    temperature    also    increases    greatly    the 
velocity  of  reactions:    in  fact  it  is  found  that,  in  a  large  number  of 
cases,  this  velocity  is  doubled  when  the  temperature  is  raised  10°. 
Reactions  in  which  catalysts  intervene  do  not  escape  the  general  rule 
and  are  greatly  accelerated  by  elevation  of  temperature  which  is  con- 
sequently favorable,  so  long  as  it  does  not  greatly  change  the  mech- 
anism of  the  reaction  —  which,  however,  frequently  happens.    Thus 
catalytic  hydrogenation  is  frequently  replaced,  above  a  certain  tem- 
perature, by  its  reverse,  catalytic  dehydrogenation. 

26.  For  example  in  the  hydrogenation  of  benzene  over  nickel,  the 
velocity  of  the  formation  of  cyclohexane  increases  rapidly  from  70°, 
where  it  is  very  slow,  up  to  180-200°,  the  most  favorable  tempera- 
ture.   From  there  on  it  decreases  as  300°  is  approached,  at  which 
this  reaction  no  longer  takes  place,  cyclohexane  being,  on  the  con- 
trary, decomposed  into  benzene  and  hydrogen  or  even  into  benzene 
and  methane  according  to  the  equation: 


this  latter  reaction  becoming  more  important  as  the  temperature  is 
raised.3* 

27.  In  the  hydrogenation  of  acetylene  which  takes  place  without 
complications  at  room  temperature   (423),  elevation  of  temperature 
tends  to  introduce,  by  the  side  of  the  transformation  into  ethane,  the 
condensation  of  acetylene  into  more  complex  molecules  even  to  the 
formation  of  solid  carbonaceous  deposits  (924). 

28.  In  the  dehydration  of  primary  alcohols  by  contact  with  anhy- 
drous oxides,  elevation  of  temperature  tends  to  introduce  or  to  accel- 
erate the  reaction  of  dehydrogenation  whereby  aldehydes  or  com- 
pounds produced  from  them  are  formed  (709). 

29.  Thus,  by  a  judicious  choice  of  reaction  temperature,  it  is  fre- 
quently possible  to  obtain,  at  will,  various  degrees  of  combination. 
For  example,  in  the  hydrogenation  of  anthracene  over  nickel,  at  180°, 
perhydroanthracene,  C14H24,  is  obtained  along  with  the  dodecahydro-  ; 
at  200°  the  octohydro-  is  prepared  and  at  260°,  the  tetrahydro-.33 

82  SABATIER,  and  SENDERENS,  Ann.  CMm.  Phys.  (8),  4,  334  (1905). 
as  GODCHOT,  Ann.  Chim.  Phys.  (8)  12,  468  (1907). 


9  CATALYSIS  IN  GENERAL  34 

30.  Pressure.     Increase  of  pressure  can  scarcely  have  any  con- 
siderable effect  except  in  gaseous  systems  or  in  heterogeneous  systems 
having  a  gaseous  phase.    In  such  cases,  it  can  be  foreseen  that  it 
will  have  a  beneficial  effect  in  those  cases  in  which  the  number  of 
molecules  is  diminished  in  the  reaction.3*    This  is  the  case  in  the 
hydrogenation  of  compounds  containing  an  ethylene  bond  and  prac- 
tical use  is  made  of  it  in  the  hydrogenation  of  liquid  fats  (956) . 

Likewise  in  the  direct  hydrogenation  of  phenol  by  nickel,  in  the 
liquid  system  around  150°,  the  formation  of  cyclohexanol  is  extremely 
slow  in  hydrogen  at  ordinary  pressure,  but,  on  the  contrary,  is  rapid 
and  complete  under  15  atmospheres.35 

31.  On  the  contrary,  molecular  decompositions  such  as  the  de- 
hydrogenation  of  alcohols  into  aldehydes  or  ketones,  in  contact  with 
finely  divided  copper,  are  favored  by  a  lowering  of  the  pressure,  which 
diminishes  also  the  reverse  reaction  (653). 

32.  Quantity  of  Catalyst.    We  must  at  once  distinguish  between 
the  two  cases,  whether  the  catalyst  acts  in  homogeneous  or  hetero- 
geneous systems. 

In  homogeneous  systems,  in  which  the  catalyst  remains  in  intimate 
mixture  with  the  components  of  the  reaction,  it  acts  by  its  mass  and 
its  action  increases  with  its  concentration. 

In  the  manufacture  of,  sulphuric  acid  by  the  lead  chamber  process, 
in  which  oxides  of  nitrogen  serve  as  the  catalyst,  the  velocity  is  pro- 
portional to  their  concentration  up  to  a  certain  limit. 

In  the  inversion  of  sugar  solutions  by  mineral  acids  (324),  and 
in  the  saponification  of  esters  by  the  same  agents  (313),  the  active 
agents  in  the  catalysis  are  the  free  hydrogen  ions  arising  from  the 
electrolytic  dissociation  of  the  acids  and  the  velocity  of  the  reaction 
is  proportional  to  the  concentration  of  these  ions. 

In  the  catalytic  decomposition  of  hydrogen  peroxide  by  small 
amounts  of  alkali,  the  rapidity  of  the  decomposition  is  nearly  pro- 
portional to  the  concentration  of  the  alkali.36 

33.  It  is  the  same  way  with  certain  solid  catalysts,  iodine  in  the 
chlorination  or  organic  compounds  (278),  and  anhydrous  aluminum 
chloride  in  the  Friedel  and  Crafts  reaction  (883),  which  do  not  act 
till  they  have  been  dissolved  in  the  liquids  of  the  system  to  be  trans- 
formed and  then  are  comparable  to  liquid  catalysts,  with  activity 
proportional  to  their  concentration. 

34.  Heterogeneous  systems  are  much  more  frequently  met  with: 

8*  DARZENS,  Bull.  Soc.  Ckim.  (4),  15,  588  (1914). 

35  BROCKET,  Ibid.  (4),  15,  554  (1914). 

86  LEMOINE,  Compt.  rend.,  161,  47  (1915). 


36  CATALYSIS  IN  ORGANIC  CHEMISTRY  10 

the  catalyst  in  such  is  a  solid  phase  in  a  liquid  or  gaseous  medium 
and  exercises  its  useful  power  only  on  its  surface.  The  action,  at  first 
sight,  depends  on  the  extent  of  the  surface,  or  at  least  on  the  mass 
of  an  extremely  thin  layer.  A  layer  of  silver  0.0002  mm.  thick,  de- 
posited on  glass,  causes  a  very  rapid  decomposition  of  hydrogen 
peroxide.37 

35.  Solid  catalysts  are  more  active  the  greater  their  surface,  and, 
for  the  same  weight,  the  finer  their  grains;  but  there  is,  by  no  means, 
a  rigorous  proportionality  between  the  activity  and  the  extent  of 
surface. 

In  liquids,  convection  currents  which  bring  the  material  to  be 
transformed  into  more  or  less  perfect  contact  with  the  catalysts, 
have  an  important  influence  on  the  rate  of  the  reaction,  but  one  dif- 
ficult to  estimate.  If  the  mixture  is  kept  perfectly  homogeneous,  the 
active  surface  of  a  given  catalyst,  made  up  of  grains  of  the  same  size, 
should  be  proportional  to  the  number  of  grains,  that  is  to  say,  to  the 
total  mass,  but  should  increase  very  rapidly  as  the  grains  become 
smaller. 

For  a  solid  catalyst  acting  in  a  gaseous  system,  the  incessant  and 
very  rapid  movement  of  the  gas  particles  is  sufficient  to  assure  the 
homogeneity  of  the  system.  The  activity  of  the  catalyst,  if  it  is  in 
a  very  thin  layer,  is  proportional  to  the  area  of  this  layer.  If  the 
layer  is  thick,  not  only  the  surface  particles  act  but  also  those  within, 
the  effect  of  the  interior  particles  being  more  important,  in  propor- 
tion as  the  grains  which  compose  the  catalytic  material  are  lighter 
and  less  agglomerated.  With  a  solid  in  a  fine  powder,  which  is 
readily  penetrated  by  the  gas,  the  useful  surface  is  extremely  large 
as  compared  with  the  exterior  surface  of  the  layer.  The  state  of 
division  of  a  solid  catalyst  is  a  matter  of  prime  importance.  The 
catalytic  power  of  nickel  in  sheets  or  even  in  thin  foil  is  quite  minute 
and  of  no  practical  value,  while  it  is  highly  developed  in  the  finely 
divided  nickel  which  is  obtained  by  reducing  nickel  oxide  by  hydro- 
gen, below  red  heat,  and  particularly  so  when  the  oxide  obtained  by 
dehydration  of  nickel  hydroxide  is  itself  finely  divided. 

From  this  point  of  view,  there  are  great  differences  in  various 
catalysts  according  to  the  conditions  of  their  preparation  (see 
Chapter  II). 

87  LEMOINE,  Ibid.,  155,  15  (1912). 


CHAPTER   II 
ON    CATALYSTS 

36.  As  chemistry  has  developed,  the  number  of  catalytic  phe- 
nomena has  increased  enormously  and  it  has  been  recognized  that 
the  role  of  catalyst  is  played,  not  by  a  few  bodies  only  but  by  a  mul- 
titude of  substances  of  every  sortr 

37.  Solvents.    The  definition  proposed  by  Ostwald,  "A  catalyst 
is  a  substance  which,  without  appearing  in  the  final  product,  influ- 
ences the  velocity  of  a  reaction,"  leads  us  to  consider  an  infinite  num- 
ber of  substances  as  catalysts.    Solvents,  whatever  their  nature,  are 
catalysts  since  they  do  not  appear  in  the  equation  of  the  reaction 
which  they  cause  to  take  place. 

In  the  absence  of  a  liquid  which  dissolves  them  and  thus  realizes 
the  contact  which  is  indispensable  to  combination,  solid  substances 
which  have  no  appreciable  vapor  pressure  in  the  cold,  are  incapable 
of  reacting  with  each  other. 

Dry  crystals  of  oxalic  acid  and  chromic  anhydride  can  be  mixed 
cold  without  any  chemical  change,  but  the  addition  of  water  which 
establishes  perfect  contact  between  the  two  substances,  immediately 
starts  the  oxidation  of  the  oxalic  acid  at  the  expense  of  the  chromic 
anhydride.  The  water  may  be  recovered  completely  and  unchanged 
by  the  reaction.  It  acts  as  a  catalyst. 

38.  The  nature  of  the  solvent  can  change  greatly  the  velocity  of 
reactions  which  take  place  in  it,  and  furthermore,  the  influence  which 
it  exercises  is  absolutely  special  in  each  case. 

Water  is  a  true  catalyst  in  the  decomposition  of  hydrogen 
peroxide.1 

In  the  fixation  of  hydrogen,  by  colloidal  palladium,  upon  the  acet- 
ylene triple  bond,  the,  solvent  has  an  important  influence  of  its  own.2 

The  combination  of  triethyl-amine  with  ethyl  iodide  to  form 
tetraethyl-ammonium  iodide  at  100°,  is  203  times  as  rapid  in  ethyl 
alcohol,  718  times  in  acetophenone,  and  742  times  in  benzyl  alcohol, 
as  it  is  in  hexane.3 

1  LEMOINE,  Compt.  rend.,  155,  9  (1912). 

2  ZAI/KIND  and  PISCHIKOV,  Jour.  Russian  Phys.  Chem.  Soc.,  46,  1527  (1914), 
C.  A.,  9,  2067. 

8  MBNSCHTJTKIN,  Zeit.  phys.  Chem.,  i,  611  (1887);  6,  41  (1890). 

11 


39  CATALYSIS  IN  ORGANIC  CHEMISTRY  12 

39.  In  reversible  reactions,  the  limit  will  not  be  altered  by  a 
change  of  solvent  if  this  does  not  react  in  any  way  with  either  the 
reactants  or  the  products:    otherwise  the  limit  will  be  modified.    For 
example,  in  reactions  between  electrolytes,  brought  about  in  alcohol 
or  in  water,  electrolytic  dissociation  is  of  great  influence  in  case  water 
is  the  solvent. 

40.  Solvents  are  not  commonly  classed  with  true  catalysts  as  this 
designation  is  usually  reserved  for  those  substances  which  act  in 
small  concentration  and  of  which  a  small  quantity  is  able  to  cause 
large  quantities  of  other  materials  to  react. 

DIVERSE    SUBSTANCES    CAN    ACT    AS 
CATALYSTS 

41.  The  number  of  substances  capable  of  acting  as  catalysts,  is 
already  very  large  and  continues  to  increase  with  the  progress  of 
chemistry. 

We  find  in  this  class  the  most  varied  materials:  elements,  oxides, 
mineral  acids,  bases,  metallic  chlorides,  bromides,  iodides,  fluorides 
and  oxygen  salts,  ammonia  and  its  derivatives,  and  diverse  organic 
compounds.  But,  particularly  for  solids,  the  catalytic  activity  can 
vary  greatly  according  to  their  origin,  either  if  they  can  exist  in  dis- 
tinct molecular  forms,  or,  more  frequently,  if  they  present  them- 
selves in  different  states  of  sub-division  (32). 

ELEMENTS    AS    CATALYSTS 

42.  Elements  which  are  of  themselves  true  catalysts,  maintaining 
themselves  unchanged  during  the  course  of  the  reactions  which  they 
provoke,  are  quite  numerous  and  it  is  convenient  to  consider  along 
with  them  those  which  pass  immediately  into  compounds  which  act 
as  catalysts.    This  is  the  case  with  chlorine,  bromine,  iodine,  tel- 
lurium,  sulphur,   and   phosphorus    among   the   non-metals    and   tin, 
antimony,  and  thallium  among  the  metals. 

43.  Chlorine  and   Bromine.    These  probably   act  by  the  im- 
mediate formation  of  the  hydro-acids,  to  transform  aldehydes  into 
the  polymeric  paraldehydes. 

44.  Iodine.    Iodine  acts  in  the  same  way  in  the  same  reactions. 
It  is  frequently  employed  in  chlorinations,  and  acts  then  by  trans- 
forming itself  into  the  trichloride  which  is  the  real  factor  in  the  ca- 
talysis.   It  permits  the  direct  sulphuration  of  aromatic  amines  with 
the  elimination  of  hydrogen  sulphide  (296).    It  can  aid  in  causing 


13  ON  CATALYSTS  49 

the  condensation  of  aromatic  amines  with  naphthols  (790) .  It  serves 
also  to  facilitate  the  reaction  in  the  preparation  of  the  organo- 
magnesium  halides  of  the  Grignard  reagent,  when  it  is  desired  to  pre- 
pare these  from  chlorides  or  bromides  (302). 

45.  Sulphur  and  Tellurium.     Employed  as  carriers  in  chlorina- 
tion,  they  certainly  act  in  consequence  of  the  initial  formation  of  an 
equivalent  amount  of  the  chlorides.    Tellurium  has  been  proposed  as 
an  agent  in  direct  oxidation  (251). 

46.  Phosphorus.     Red    phosphorus    has    been    mentioned    as    a 
catalyst  for  the  dehydration  of  alcohols  above  200°    (699).       The 
chief  factor  in  this  catalysis  appears  to  us  to  be  the  small  quantity 
of  acids  of  phosphorus  which  exist  in  the  phosphorus  or  which  are 
produced  from  it  by  the  oxidising  effect  of  the  alcohol. 

47.  Antimony,  Tin  and  Thallium.     Their  use  in  chlorination  is 
based  on  the  primary  formation  of  their  perchlorides. 

48.  Carbon.    All  the  porous  forms  of  carbon  have  been  employed 
as  catalysts. 

The  carbonaceous  mass  obtained  by  calcining  blood  with  potas- 
sium carbonate  is  a  good  catalyst  for  chlorination.4 

Animal  charcoal  is  a  mediocre  catalyst  for  the  dehydration  of 
alcohols  (699) ,  but  is  efficient  in  the  preparation  of  carbonyl  chloride 
from  carbon  monoxide  and  chlorine  (282). 

Coke  may  serve  as  an  oxidation  catalyst  (258). 

Wood  charcoal,  or  baker's  charcoal  possesses  considerable  absorb- 
ing power  for  many  gases,  the  consequence  of  which  is  frequently  the 
production  of  special  reactions.  Carbon  saturated  with  oxygen  can 
produce  oxidations:  ethyl  alcohol  is  changed  to  acetic  acid.  Ethyl- 
enic  hydrocarbons  are  partially  burned.5 

Carbon  saturated  with  chlorine  enables  us  to  chlorinate  sulphur 
dioxide  in  the  cold  as  well  as  hydrogen.6 

Baker's  charcoal  catalyzes  the  decomposition  of  primary  alcohols 
above  380°,  giving,  at  the  same  time,  aldehydes  and  ethylene  hydro- 
carbons (679).  It  is  frequently  employed  for  the  preparation  of 
carbonyl  chloride  (282). 

49.  The  porosity  of  the  carbon  has  a  great  influence.    Thus  in 
the  case  of  30  volume  hydrogen  peroxide  of  which  the  half  decompo- 
sition at  17°  required  240  hours,  the  addition  of  5%  of  cocoanut 
charcoal  (in  pieces  1  to  2  mm.  in  size)  reduced  this  time  to  15.4  hours, 
while  the  same  weight  of  charcoal  from  the  black  alder  lowered  it 

4  DAMOISEAU,  Compt.  rend.,  83,  60   (1876). 
6  CALVERT,  Ibid.,  64,  1246  (1867). 
6  MELSENS,  Ibid.,  76,  92  (1873). 


50  CATALYSIS  IN  ORGANIC^CHEMISTRY  14 

only  to  212  hours.    Sugar  charcoal  falls  between  these  two  as  an 
activator.7 

50.  Sodium  brings  about  the  isomerization  of  unsaturated  hydro- 
carbons, e.  g.,  diethylallene  into  diethylallylene  (192).    It  polymerizes 
isoprene  (213)  as  well  as  acetonitrile  (231). 

51.  Magnesium.     Magnesium    powder    has    been    mentioned    as 
very  active  in  decomposing  hydrocarbons  at  600°   (918). 

Aluminum.  The  same  property  has  been  claimed  for  aluminum 
which  has  been  proposed  as  a  chlorination  catalyst  also  because  it 
changes  immediately  to  the  chloride.  Aluminum  turnings  are  only 
a  mediocre  catalyst  for  oxidation  (255). 

52.  Manganese.    Powdered  manganese  is   a   poor   catalyst  for 
oxidations  (255)  but  is  an  excellent  aid  to  bromination  (292). 

Zinc  turnings,  at  100°,  can  cause  the  condensation  of  acetaldehyde 
into  aldol  or  into  crotonic  aldehyde  (219).  The  same  metal  acts  as 
a  dehydrogenating  agent  on  alcohols  at  600-50°,  temperatures  at 
which  the  metal  is  melted,  a  condition  unfavorable  to  catalytic 
action  (670). 

53.  Nickel.    Employed  in  the  state  of  extremely  fine  division, 
as  is  obtained  by  the  reduction  of  the  oxides  by  hydrogen  or  carbon 
monoxide,  nickel  is  a  marvelous  catalyst,  the  manifold  activity  of 
which  has  been  established  by  the  investigations  of  Sabatier  and 
Senderens,  beginning  in  1879.    It  is  specially  suitable  for  the  direct 
hydrogenation    of   volatile    organic    compounds,    but    it   is    equally 
capable  of  producing  dehydrogenations  and  decompositions  whether 
they  are  followed  by  molecular  condensations  or  not.    Chapters  VIII, 
IX  and  XII  are  devoted  to  catalytic  reactions  effected  by  nickel. 

54.  The  metal  in  sheet  or  even  in  thin  foil  possesses  only  slight 
activity.    Catalytic  nickel  should  be  prepared  by  reducing  the  oxide, 
and  as  the  metal  so  produced  is  readily  oxidised  and  frequently  pyro- 
phoric,  it  is  generally  best  to  carry  out  the  reduction  in  the  same  tube 
in  which  the  catalysis  is  to  be  effected.    However  this  is  not  abso- 
lutely necessary,  if  the  precaution  is  taken  to  cool  the  reduced  metal 
perfectly  in  the  current  of  hydrogen,  or  better  still  in  a  current  of 
pure  nitrogen.8    The  metal  so  prepared  can  be  preserved  in  a  well- 

7  LEMOINE,  Ibid.,  162,  725  (1916). 

8  When  freshly  prepared  highly  active  nickel  is  exposed  freely  to  the  air, 
a  rapid  heating  takes  place  that  considerably  impairs  its  catalytic  activity.    The 
change  which  takes  place  in  the  nickel  is  brought  about  and  augmented  by  the 
heat  produced  by  the  catalytic  oxidation  of  the  hydrogen  occluded  and  surround- 
ing the  nickel  when  it  comes  in  contact  with  an  excess  of  oxygen  from  the  air. 
Similar  oxidation  of  hydrogen  is  well  known  in  the  presence  of  catalytic  pal- 
ladium or  platinum.    In  the  case  of  catalytic  nickel,  however,  the  heat  thus 


15  ON  CATALYSTS  67 

stoppered  bottle  for  quite  a  long  time  without  considerable  alteration. 

55.  The  activity  of  the  reduced  nickel  varies  greatly  according 
to  the  nature  of  the  oxide  and  the  manner  of  reduction.    The  metal 
is  more  active,  the  greater  its  surface;  and  the  lighter  the  oxide  and 
the  lower  the  reduction  temperature,  the  greater  is  this  surface. 

Nickel  reduced  at  a  bright  red  is  no  longer  pyrophoric  and 
possesses  a  considerably  reduced  catalytic  power. 

On  the  contrary,  that  which  comes  from  the  hydroxide  precipitated 
from  the  nitrate,  dried  and  reduced  around  250°,  has  an  excessive 
activity  along  with  maximum  alterability.  It  can  be  compared  to 
a  spirited  horse,  delicate,  difficult  to  control,  and  incapable  of 
sustained  work. 

Applied  to  phenol,  it  passes  by  cyclohexanol  and  produces  cyclo- 
hexane  to  a  large  extent.  It  tends  to  produce  molecular  dislocations 
in  bodies  submitted  to  catalysis. 

56.  An  excellent  quality  of  nickel  is  obtained  by  dissolving  the 
commercial  cubes  in  pure  nitric  acid  (free  from  hydrochloric) ,  calcin- 
ing the  nitrate  at  a  dull  red  and  reducing  at  about  300°  the  oxide 
thus  obtained.    Such  a  nickel  can  do  all  kinds  of  work  and  maintains 
its  activity  for  a  long  time. 

It  has  been  stated  that  nickel  prepared  above  350°  is  incapable 
of  hydrogenating  the  aromatic  nucleus,9  but  Sabatier  and  Espil  have 
shown  that  this  ability  is  still  possessed  by  a  nickel  prepared  at  700° 
even  when  it  is  kept  at  this  temperature  for  several  hours,  but  not 
by  nickel  prepared  by  reduction  above  750°  or  heated  for  some  time 
at  7500.10 

57.  Cobalt.    Finely  divided  cobalt,  such  as  is  obtained  by  the 
reduction  of  the  oxide  by  hydrogen,  can  be  employed  as  a  catalyst 
for  the  same  purposes  as  nickel,  but  is  less  useful  as  it  is  less  active, 


generated  in  the  presence  of  an  excess  of  oxygen,  or  air,  produces  an  oxidation 
of  the  catalyzer  to  an  extent  that  lessens  or  destroys  its  activity.  A  number  of 
experiments  were  made  in  which  freshly  prepared  nickel  catalyzer  still  in  the 
presence  of  hydrogen  was  subjected  to  the  action  of  a  Geryk  pump  which  ex- 
hausted practically  all  of  the  excess  hj'drogen  gas.  In  different  experiments  the 
catalyzer  was  then,  while  cold,  allowed  slowly  to  come  in  contact  with  carbon 
dioxide,  nitrogen,  and  air.  The  catalyzers  so  formed  were  active  and  retained 
their  activity  reasonably  well.  In  case  air  was  admitted  to  the  vacuum  vessel 
containing  the  catalyzer,  it  was  introduced  very  slowly  so  that  any  oxidation 
would  be  so  slight  as  not  to  increase  the  temperature  sufficiently  to  produce 
cumulative  oxidation.  —  M.  H.  ITTNER. 

9  DARZENS,  Corn-pi,  rend.,  139,  869  (1904);  BRUNEL,  Ann.  Chim.  Phys.  (8), 
6,  205  (1903). 

10  SABATIER  and  EPSIL,  Bull  Soc.  Chim.  (4),  15,  779  (1914). 


58  CATALYSIS  IN  ORGANIC  CHEMISTRY  16 

and  as  the  reduction  of  its  oxide  requires  a  higher  temperature,  in 
fact  above  400°. 

58.  Iron.     Reduced    iron    can   replace   nickel   in   quite    a    large 
number  of  cases,  but  disadvantages,  like  those  mentioned  for  cobalt, 
are  more   serious,  the   oxides   being   still   more   difficult  to   reduce. 
Between  400°  and  450°,  it  is  necessary  to  prolong  the  action  of  the 
hydrogen    for    six    or    seven   hours   to    obtain    complete    reduction. 
Furthermore,  the  metal  reduced  at  this  high  temperature  is  no  longer 
pyrophoric  and  retains  only  mediocre  activity.    However,  pulverized 
iron  is  a  useful  catalyst  for  decompositions  accomplished  at  a  low  red 
heat  (932). 

Iron  has  been  mentioned  as  a  chlorination  catalyst,  but  in  that 
case  it  serves  only  to  form  iron  chloride  which  is  the  real  catalyst. 

59.  Copper.     Copper,  reduced  from  its  oxide  by  hydrogen,  con- 
stitutes, on  account  of  its  ease  of  preparation,  the  low  temperature 
at  which  the  oxide  can  be  reduced,  below  180°,  and  the  regularity 
of  its  action,  a  valuable  catalyst  for  certain  reactions,  but  it  is  not 
capable  of  effecting  all  kinds.     Its  activity  also  varies  considerably 
according  to  the  method  of  production.    The  black  oxide  of  copper, 
prepared  by  roasting  the  metal  or  by  calcining  the  nitrate  at  a  bright 
red,  furnishes  by  reduction,  with  incandescence,   a   clear  red,  very 
compact  metal  with  low  catalytic  power.    By  reducing  with  a  slow 
current  of  hydrogen    (to  avoid  incandescence)    at  about  200°,  the 
tetracupric  hydroxide  —  such  as  is  precipitated  from  boiling  cupric 
salt  solutions   by   alkalies  —  a   very   light   violet   colored   metal   is 
obtained  with  much  greater  catalytic  activity.    The  very  fine  copper 
powder  which  is  commercially  prepared  for  imitation  gilding,   can 
frequently  be  used:    it  is  only  necessary  to  free  it  from  grease  by 
washing  with  ether  or  ligroine. 

This  latter  has  been  used  to  facilitate  several  of  the  reactions  of 
aromatic  diazonium  salts  in  which  nitrogen  is  eliminated  (606).  It 
is  efficient  in  causing  the  production  of  phenyl  oxide  by  the  action  of 
brombenzene  on  sodium  phenylate  (904). 

Copper  in  spirals,  or  in  gauze,  has  been  employed,  with  advantage, 
in.  the  catalytic  oxidation  of  alcohols,  ethers,  hydrocarbons,  and 
amines  (254). 

60.  Silver.    Silver  powder  is  an  excellent  oxidation  catalyst  (253) . 
Inversely,  it  causes  the  rapid  decomposition  of  hydrogen  peroxide, 
transforming    itself    into    the    oxide    Ag403    which    continues    the 
catalysis.11 

61.  Platinum.    Platinum  is  one  of  the  longest  known  catalysts. 
11  BERTHELOT,  Bull  Soc.  Chim.  (2),  34,  135  (1880). 


17  ON  CATALYSTS  63 

Not  oxidisable  in  the  air  at  any  temperature,  it  is  a  powerful  catalyst 
for  oxidation  or  for  hydrogenation,  especially  when  it  is  finely  divided 
and  presents  a  large  surface.  This  is  the  condition  realized  in 
platinum  sponge,  a  porous  material  obtained  by  calcining  ammonium 
chlorplatinate,  and  even  better  in  platinum  black  and  in  colloidal 
platinum,  which  can  be  mixed  intimately  with  liquids  submitted  to 
catalysis  (67). 

62.  Platinum  black   can  be   prepared   either  by  reducing  acid 
solutions  of  platinic  chloride12  by  zinc,  or  better  by  magnesium,  or 
by  treating  the  platinum  chloride  with  alcohol  and  alkalies,13  or  by 
reducing  the  platinum  salt  with  sodium  formate,14  or  with  sodium  tar- 
trate,  or  even  with  glucose  in  alkaline  solution,  or  by  glycerine  and 
potash.15 

An  excellent  method  is  that  of  Loew:  35  cc.  formalin  is  added  to 
25  g.  platinum  chloride  dissolved  in  30  cc.  water  and  then,  little  by 
little,  while  cooling  25  g.  caustic  soda  dissolved  in  its  own  weight  of 
water.  After  twelve  hours  it  is  filtered  off  and  washed.  A  spongy 
mass  is  thus  obtained  which  is  dried  in  the  cold  over  sulphuric  acid.16 

Platinum  black  always  retains  traces  of  substances  with  which 
it  has  been  in  contact  during  its  preparation.  Blacks  prepared  in 
alkaline  solution  are  more  active  than  those  from  acid  solution. 

63.  According  to  Lemoine  the  grains  of  platinum  black,  of  which 
the  diameter  is  about  0.1  mm.,  are  much  more  active  than  those  of 
the  sponge  for  the  same  area.    With  a  specimen  of  hydrogen  peroxide 
which,  without  catalyst,  required  ten  days  for  half  decomposition, 
this  time  was  reduced  by  platinum  black  to  0.00013  hour  and  with 
the  same  surface  of  the  sponge  only  to  0.2  hour.    The  black  possesses 
a  specific  activity  which  is,  without  doubt,  due  to  less  molecular 
condensation  and  which  disappears  when  it  is  heated  to  400  to  500 °.17 

This  weakening  by  heating  is  progressive.  Thus  platinum  black 
is  not  sensibly  altered  as  a  hydrogenation  catalyst  when  heated  below 
300°  and  still  retains  its  power  to  transform  limonene  into  menthane 
by  the  fixation  of  2H2.  If  it  is  heated  to  430°,  it  is  considerably 
weakened  and  can  add  only  H2  to  the  external  double  bond,  giving 
carvomenthene.  Heated  to  500°,  it  loses  all  activity.18 

12  BOETTGER,  J.  Prakt.  Chem.  (2),  2,  137  (1870). 

13  ZEISE,  Pogg.  Ann.,  9,  632  (1827). 

i*  DOEBEREINER,  Ibid.,  28,  181   (1833). 

15  ZDRAWKOWITCH,  Bull.  Soc.  Chim.  (2),  25,  198  (1876). 

16  LOEW,  Berichte,  23,  289  (1890).    Improved  directions  for  this  important 
preparation  are  given  by  WILLSTATTER  and  WALDSCHMIDT-LEITZ  in  Berichte,  54, 
121  (1921).  — E.  E.  R. 

17  LEMOINE,  Compt.  rend.,  162,  657  (1916). 

18  VAVON,  Ibid.,  158,  409  (1914). 


64  CATALYSIS  IN  ORGANIC  CHEMISTRY  18 

Compact  platinum  in  foil  or  wire  has  a  certain  activity,  at  least,  if 
it  has  been  previously  heated  above  50°.  A  heated  platinum  spiral 
introduced  into  a  mixture  of  alcohol  vapor  and  air  or  oxygen,  causes 
the  formation  of  aldehyde  and  the  incandescence  which  results  from 
the  heat  liberated  in  the  oxidation,  maintains  itself  indefinitely  so 
long  as  the  mixture  is  renewed:  this  is  the  lamp  without  flame.™ 

64.  Rhodium,   Ruthenium,   Iridium,  and   Osmium.     Employed 
in  the  form  of  the  pulverulent  black,  or  as  sponge,  these  metals  act 
in  the  same  manner  as  platinum,  at  least  as  regards  reactions  of  oxida- 
tion or  of  decomposition,  but  they  are  less  active  in  hydrogenation 
(580). 

Rhodium  or  iridium  black  decomposes,  in  the  cold,  formic  acid 
into  hydrogen  and  carbon  dioxide  (822).  In  contact  with  alcohol 
and  caustic  soda,  hydrogen  is  evolved  with  the  formation  of  sodium 
acetate.20 

65.  Palladium.    Palladium   exhibits   the   property    of   absorbing 
very  large  quantities  of  hydrogen,  even  up  to  930  times  its  own 
volume.21     Palladium  thus  saturated  with  hydrogen  can  effect  a  large 
number  of  hydrogenations.     But  the  metal  can  serve  also  as  a  tem- 
porary support  for  hydrogen,  that  is  to  say,  as  a  hydrogenation  cat- 
alyst, in  the  form  of  sponge  or  black  (573) ,  and  can  be  employed  as 
a  catalyst  for  dehydrogenation   (669),  for  decomposition   (624),  or 
for  polymerization  (212). 

66.  Gold.     Gold,  when  finely   divided,   has   catalytic   properties 
resembling  those  of  silver. 

67.  Colloidal  metals.    The  catalytic  activity  of  metals,  being  in 
direct  relation  to  the  extent  of  their  surfaces,  consequently  to  the 
minuteness  of  their  particles,  should  reach  its  maximum  in  the  col- 
loidal state.    As  the  chemical  alterability  of  the  metals  is  also  inten- 
sified by  their  extreme  subdivision,  it  would  hardly  be  expected  that 
any  could  be  practically  used  in  this  state  except  those  not  oxidisable 
in  the  cold,  such  as  platinum,  palladium,  gold  and  silver. 

68.  Bredig 22  has  described  a  simple  method  for  preparing  colloidal 
metals:    an  electric  arc  is  made  to  play  between  two  wires  of  the 
metal  under  pure  water.    A  sort  of  nebulosity  is  observed  which 
becomes  darker  and  darker  till  it  is  soon  so  opaque  that  the  spark 

19  HOFMANN,  Annalen,  145,  358  (1868). 

20  SAINTE-CLAIRE-DEVILLE  and  DEBRAY,  Compt.  rend.,  78,  1782  (1874). 

21  GRAHAM,  Phil  Mag.,  (4),  32,  401  and  503  (1866);  36,  63  (1868).    Proc. 
Roy.  Soc.,  15,  223,  502  (1867);  16,  429  (1868);  17,  212  and  500  (1869).    Compt. 
rend.,  63,  471  (1866)  and  68,  101  (1869). 

22  BREDIG,  Zeit.  physik.  Chem.,  31,  258  (1899);  37,  1,  323  (1901);  Berichte, 
37,  798  (1904);  Zeit.  Elektroch.,  14,  51   (1908). 


19  ON  CATALYSTS  71 

can  not  be  seen.  Solutions  thus  obtained  can  be  preserved  for  a  long 
time  and  contain  0.09  to  0.02  g.  gold  per  liter  and  a  less  amount  of 
palladium  or  platinum:  the  number  of  particles  in  such  a  solution 
may  reach  as  high  as  a  billion  per  cubic  millimeter. 

69.  Unfortunately  such  solutions  are  unstable  in  the  presence  of 
various  substances.    The  presence  of  suitable  organic  materials  gives 
them  stability  and  Paal  has  found  that  egg  albumen  has  this  effect. 
He  dissolves  15  parts  of  caustic  soda  in  500  parts  of  water,  adds  100 
parts  egg  albumen  and  warms  on  the  water  bath  till  solution  is  nearly 
complete.    It  is  acidulated  with  sulphuric  acid  and  the  precipitate 
filtered  off.    The  solution  is  neutralized  with  soda,  evaporated  on 
the  water  bath  to  a  small  volume  and  again  acidulated  with  sulphuric 
acid. 

The  filtered  solution  is  dialyzed  to  separate  the  sodium  sulphate. 
The  liquid  remaining  in  the  dialyzer  is  treated  warm  with  baryta 
water  which  precipitates  the  remaining  sulphate  ions.  The  filtered 
solution  is  evaporated  on  the  water  bath  and  several  volumes  of 
alcohol  added,  which  precipitates  white  flakes  which  Paal  has  named 
lysalbinic  acid.  When  dry,  this  is  a  white  powder,  soluble  in  water 
and  nearly  insoluble  in  alcohol:  its  weight  is  about  one-fourth  that 
of  the  albumen. 

One  gram  of  the  above  product  is  dissolved  in  30  cc.  water  and 
made  alkaline  with  a  slight  excess  of  soda,  2  g.  platinum  chloride  dis- 
solved in  a  little  water  is  added  and  then  a  slight  excess  of  hydrazine 
hydrate.  The  solution  turns  dark  and  a  gas  is  evolved:  after  five 
hours  it  is  dialyzed  to  eliminate  electrolytes,  carefully  evaporated  on 
the  water  bath  and  dried  in  vacuum.  Brilliant  black  scales  are 
obtained  which  dissolve  in  water  to  form  a  black  opaque  solution: 
this  is  colloidal  platinum. 

Colloidal  palladium  is  prepared  in  an  analogous  manner.28 

Solutions  of  these  are  very  stable  and  can  even  be  heated  for  a 
long  time  .without  change. 

70.  In  this  way  colloidal  solutions  can  be  prepared  of  silver,  gold, 
copper,  osmium,  and  iridium,  all  decomposing  hydrogen  peroxide  with 
extreme  energy.    Traces  of  osmium  produce  this  effect.24 

71.  Skita  prepared  a  colloidal  palladium  hydroxide,  for  use  as  a 
hydrogenation  catalyst,  by  heating  to  boiling  a  solution  of  palladium 
chloride,  PdCl2,  with  soda  and  a  little  gum  arabic.    The  solution  is 

28  PAAL,  Berichte,  35,  2195  (1902).  PAAL  and  AMBERGER,  Ibid.,  37,  126  (1904) 
and  38,  1398  (1905).  KELBER  and  SCHWARTZ,  Ibid.,  45,  1946  (1912).  SKITA  and 
MEYER,  Ibid.t  45,  3579  (1912). 

24  PAAL  and  AMBERGER,  Berichte,  40,  2201  (1907).  PAAL,  BIEHLER  and  STEYER, 
Ibid.,  50,  722  (1917). 


72  CATALYSIS  IN  ORGANIC  CHEMISTRY  20 

dialyzed  till  neither  silver  nitrate  nor  baryta  water  gives  a  test  out- 
side. The  solution,  evaporated  to  dryness  in  a  vacuum,  gives  brown 
scales  of  colloidal  palladium  hydroxide,  insoluble  in  cold  water  but 
soluble  in  water  containing  traces  of  acid  or  alkali. 

Another  method  of  preparing  colloidal  palladium,  given  by  the 
same  author,  is  to  pass  a  current  of  hydrogen  through  a  warm  solu- 
tion of  palladous  chloride  and  gum  arabic. 

A  colloidal  platinum  hydroxide,  analogous  to  that  of  palladium, 
is  obtained  by  treating  a  boiling  solution  of  potassium  chlorplatinate 
with  the  theoretical  amount  of  decinormal  soda  and  adding  gum 
arabic.  The  brown  solution  by  dialysis,  and  evaporation  in  vacuum, 
gives  a  black  solid,  insoluble  in  water  but  made  soluble  by  a  trace 
of  alkali. 

The  solutions  so  obtained  can  be  neutralized,  dialyzed  and  evap- 
orated in  vacuum:  the  black  scales  so  obtained  dissolve  readily  in 
water  and  can  be  employed  for  hydrogenations  in  acid  media  (561). 
The  solutions  are  not  coagulated  by  boiling  with  acetic  acid,  nor  by 
heating  with  water  under  pressure. 

In  another  process,  called  the  germ  method,  the  same  chemist  adds 
to  a  solution  of  platinum  chloride,  PtCl4,  containing  gum  arabic,  a 
trace  of  a  previously  prepared  colloidal  platinum  in  solution,  and 
submits  the  liquid  to  the  action  of  compressed  hydrogen,  by  which 
means  a  colloidal  solution  of  the  metal  is  obtained.25 

72.  Among  colloidal  metals,  the  maximum  activity  for  oxidations 
belongs  to  platinum,  osmium  being  only  slightly  active:  26  for  hydro- 
genations, silver  and  osmium  are  much  inferior  to  platinum  and 
particularly  to  palladium;  gold  and  copper  produce  no  effect.27 


OXIDES    AS    CATALYSTS 

73.  Water.  Water  appears  frequently  as  a  positive  catalyst: 
quite  a  large  number  of  reactions  are  not  readily  carried  out  except 
in  the  presence  of  traces  of  moisture.  Oxidations  are  generally  more 
difficult  to  realize  by  means  of  oxygen  rigorously  dried.28  A  mixture 
of  absolutely  dry  carbon  monoxide  and  oxygen  can  not  be  made  to 
explode.  A  flame  of  carbon  monoxide  is  extinguished  in  perfectly 
dry  air.29  Carbon  and  even  phosphorus  refuse  to  burn  in  perfectly 

25  SKITA,  Berichte,  45,  3312   (1912). 

26  PAAL,  Berichte,  49,  548  (1916). 

27  PAAL  and  GBRUM,  Berichte,  40,  2209  (1907). 

28  DDCON,  Proc.  Roy.  Soc.,  37,  56  (1884). 
2»  TRAUBE,  Berichte,  18,  1890  (1885). 


21  ON  CATALYSTS  75 

dry  oxygen.30  Hydrogen  and  oxygen  thoroughly  dried  do  not  com- 
bine up  to  1000°.  Ammonia  and  hydrogen  chloride  when  rigorously 
freed  from  moisture  do  not  form  any  solid  ammonium  chloride  and, 
conversely,  thoroughly  dry  ammonium  chloride  can  be  volatilized 
without  decomposition  and  the  density  of  its  vapor  is  then  normal.31 

A  trace  of  moisture  is  sufficient  to  cause  the  transformation  of 
vitreous  arsenic  trioxide  into  its  octahedral  isomer  (porcelain  like).32 

Absolutely  dry  fluorine  does  not  attack  glass  (Moissan). 

This  beneficial  catalytic  effect  of  water  is  quite  exceptional  in 
organic  reactions,  but  we  may  mention  that  in  the  catalytic  oxidation 
of  methyl  alcohol  vapors  by  a  platinum  spiral,  the  presence  of  water 
favors  the  production  of  formaldehyde.  With  absolute  methyl  alco- 
hol, incandescence  is  not  produced  unless  the  spiral  has  an  initial 
temperature  of  at  least  400°,  while  with  20%  of  water  in  the  alcohol, 
175°  is  sufficient.33 

74.  Sulphur  Dioxide.    Small  amounts  of  this  gas  are  sufficient  to 
cause    the    polymerization    of    acetaldehyde    into    par  aldehyde    or 
metaldehyde  (482). 

75.  Anhydrous   Metallic   Oxides.    Manganese  dioxide   rapidly 
decomposes  hydrogen  peroxide,  without  itself  being  altered.    The 
same  is  true  of  the  yellow  oxide  of  lead  in  alkaline  solution.    Cuprous 
oxide  is  an  active  catalyst  for  the  decomposition  of  diazonium  salts 
(606). 

The  studies  that  have  been  made  in  commercializing  the  contact 
process  for  sulphuric  acid,  discovered  in  1831  (4),  have  shown  that 
various  finely  divided  metallic  oxides  may  be  substituted  for  the 
platinum.  As  early  as  1852,  Wohler  and  Mahla  suggested  for  this 
purpose,  oxides  of  iron,  chromium  and  copper;  and  Petrie,  Plattner, 
and  Reich  advised  the  use  of  pulverized  silica.34  In  1854,  Torn- 
thwaite  proposed  manganese  oxide. 

The  application  of  anhydrous  metallic  oxides  to  the  catalytic 
oxidation  of  volatile  organic  compounds  was  proposed  anew  in  1906 
by  Sabatier  and  Mailhe,  who  mentioned  specially  the  oxides  of  copper, 
nickel,  cobalt,  chromium,  manganese  and  uranium  (260).  Matignon 
and  Trannoy  made  the  same  suggestion  (260). 

Several  anhydrous  metallic  oxides,  particularly  alumina,  thoria, 
blue  oxide  of  tungsten,  titania  and  zirconia,  etc.,  are  endowed  with 

so  BAKER,  J.  Chem.  Soc.,  47,  349  (1886). 

81  BAKER,  Ibid.,  65,  611  (1894). 

82  WINKLER,  J.  pr.  Chem.  (2),  31,  247  (1885). 

83  TRILLAT,  Bull.  Soc.  Chim.,  (3),  29,  35  (1903). 

34  Silica  gel  has  been  found  by  Patrick  to  be  an  excellent  catalyst  for  the 
oxidation  of  nitric  oxide  by  oxygen.  —  E.  E.  R. 


76  CATALYSIS  IN  ORGANIC  CHEMISTRY  22 

important  catalytic  activity  towards  alcohols,  which  they  can  decom- 
pose into  unsaturated  hydrocarbons  (701).  They  can  catalyze  the 
synthesis  of  thiols  (743),  amines  (732),  ethers  or  phenol  ethers  (786 
and  789)  and  esters  (762).  These  oxides  and  manganese  oxide, 
employed  as  catalysts  with  acids  produce  symmetrical  ketones  (837) , 
mixed  ketones  (847),  aldehydes  (851)  and  decompose  esters  (858). 
They  can  also  bring  about  the  isomerization  or  polymerization  of 
unsaturated  hydrocarbons  (211). 

76.  The  catalytic  power  of  these  various  oxides  is  very  variable, 
according  to  the  method  of  preparation. 

Catalysis  being  a  matter  of  surface,  the  amorphous  oxides  prepared 
from  precipitated  hydroxides,  dehydrated  at  low  temperatures,  are 
much  more  active  than  crystallized  oxides  or  those  that  have  been 
sintered  together  by  calcination  at  a  red  heat. 

These  latter  possess,  for  equal  mass,  a  much  smaller  surface  and 
are  frequently,  without  doubt,  in  an  advanced  stage  of  molecular 
condensation.  This  is  particularly  true  of  the  oxides  of  the  metals 
of  small  atomic  weight,  aluminum,  iron,  silicon,  chromium,  etc.  The 
action  of  acids  has  long  shown  such  differences. 

77.  Amorphous  alumina,  obtained  by  dehydrating  the  hydroxide 
below  400°,  dissolves  readily  in  mineral  acids  and  is  an  active  catalyst 
for  alcohols,  while  crystallized  alumina  and  amorphous  alumina  cal- 
cined at  a  bright  red,  are  insoluble  in  acids  and  have  almost  no 
catalytic  power  for  alcohols. 

Analogous  differences  are  observed  with  the  different  varieties  of 
silica,  though,  for  the  decomposition  of  hydrogen  peroxide,  silica  cal- 
cined at  red  heat  is  more  active  than  the  dried  silica.86 

Ferric  oxide  prepared  by  dehydrating  the  precipitated  hydroxide 
below  350°,  is  a  much  more  powerful  catalyst  for  alcohols  than  that 
obtained  at  a  red  heat.36 

It  is  the  same  with  regard  to  hydrogen  peroxide  of  which  the 
former  decomposes  50%  in  10  seconds,  while  the  latter  requires  1550 
seconds. 

78.  Furthermore,  the  very  nature  of  the  catalyst  is  modified  by 
these  changes  of  constitution  of  the  oxides. 

The  sesquioxide  of  chromium,  prepared  by  dehydrating  the  blue 
precipitated  hydroxide,  gives  with  ethyl  alcohol  4.2  cc.  gas  per  minute 
containing  91%  of  ethylene,  while,  after  calcination  at  500°,  the  same 
oxide  furnishes  only  2.8  cc.  gas  with  40%  ethylene.  The  oxide  pre- 

35  LEMOINE,  Compt.  rend.,  162,  702  (1916). 

36  SABATIEB  and  MAILHE,  Ann.  Chim.  Phys.,  (8),  20,  313  (1910). 


23  ON  CATALYSTS  81 

pared  by  the  explosion  of  ammonium  bichromate  and,  consequently 
formed  with  incandescence,  gives  1.2  cc.  gas,  with  38%  ethylene.37 

The  crystallized  oxide  gives  no  gas  at  all  at  350°,  and  400°  must 
be  reached  to  obtain  2  cc.  which  is  then  nearly  pure  hydrogen.  The 
catalytic  function  is  modified  at  the  same  time  that  it  is  weakened.38 

Analogous  variations  have  been  observed  with  silica  and  alumina, 
both  in  the  intensity  and  in  the  direction  of  the  decomposition,39  and 
a  relation  has  been  noted  between  the  catalytic  activity  of  alumina 
and  its  solubility  in  acids.40 

79.  Thoria,  on  the  contrary,  does  not  present  this  inconvenience 
and  its  activity  is  not  sensibly  diminished  when  it  is  calcined  at  a 
red  heat:    it  appears  that  such  a  heavy  molecule  can  not  suffer 
important  polymolecular  condensations. 

80.  Nickel  oxide  and  especially  nickel  suboxide,  which  results 
from  the  incomplete  reduction  of  the  monoxide,  have  been  regarded 
by  some  chemists  as  the  best  catalysts  for  carrying  out  the  hydro- 
genation  of   organic  compounds  in   a   liquid  medium.    At  least  as 
active  as  reduced  nickel,  they  have  the  advantage  of  being  less  alter- 
able and  consequently  of  retaining  their  catalytic   activity   longer 
(584) .    The  researches  of  Sabatier  and  Espil  have  indeed  established 
the  existence  of  a  suboxide,  apparently  Ni40,  which  is  the  first  step 
in  the  reduction  of  the  monoxide,  but  they  have  shown  that  this  sub- 
oxide,  while  it  is  being  formed,  is  partially  reduced  to  the  metal  and 
it  is  this  latter  which  is  the  sole  factor  in  the  hydrogenations  that 
have  been  attributed  to  the  oxide.41 

The  same  reservations  should  be  applied  to  the  oxide  of  osmium, 
which  has  been  proposed  as  a  hydrogenation  catalyst  (583)  and 
which,  doubtless,  serves  only  as  a  source  of  finely  divided  osmium.*2 

MINERAL   ACIDS 

81.  Strong  mineral  acids  frequently  act  as  catalysts  in  chemical 
reactions. 

Hydrochloric  and  sulphuric  acids,  employed  in  small  amounts, 
bring  about  the  rapid  esterification  of  alcohols  by  organic  acids  (749). 
Hydrochloric  acid  shows  itself  also  efficacious  for  the  production  of 
acetals  from  alcohols  (782)  as  well  as  of  similar  compounds  from 

87  LEMOINE,  Compt.  rend.,  162,  702  (1916). 

88  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.,  (8),  ao,  339  (1910). 
8»  SENDERENS,  Bull.  Soc.  Chim.,  (4),  3,  823  (1908). 

40  IPATIEF,  Berichte,  37,  2986  (1904). 

41  SABATIER  and  ESPIL,  Compt.  rend.,  158,  668  (1914)  and  159,  140  (1914). 
*2  NORMANN  and  SCHICK,  Arch.  Pharm.,  252,  208  (1914),  C.  A.,  8,  3129. 


82  CATALYSIS  IN  ORGANIC  CHEMISTRY  24 

glucose  with  alcohols  and  thiols.43  It  also  causes  catalytic  dehydra- 
tions in  the  condensation  of  ketones  (795)  and  in  analogous  reactions. 

Sulphuric  acid  behaves  similarly  in  the  crotonization  of  aldehydes 
and  in  similar  condensations. 

These  two  acids  intervene  in  a  similar  manner  in  the  acetylation 
of  amines,  e.  g.  of  urea.  Acetanhydride,  without  catalyst,  gives  a 
yield  of  only  19.3%,  but  73.3%  with  one  molecule  of  hydrochloric 
acid,  and  61%  with  one  molecule  of  sulphuric  acid.44 

82.  But  these  acids  more  frequently  accomplish  the  reverse  cat- 
alysis in  causing  hydrolysis,  or  decomposition  by  addition  of  water, 
and  this  aptitude  they  have  in  common  with  all  strong  soluble  mineral 
acids,  because  it  is  in  consequence  of  their  ionization  and  should  be 
considered  as  due  to  the  hydrogen  ions  which  they  furnish.    Their 
hydrolytic  activity  is  proportional  to  their  electrolytic  dissociation. 

We  have  cases  of  this  decomposition  by  the  addition  of  water, 
in  the  various  catalytic  effects  of  acids  in  the  saponification  of  esters 
and  fats  (314),  the  hydrolysis  of  amides  (331),  of  anilides,  of  cer- 
tain aromatic  sulphonic  acids,45  of  acetals,  in  the  inversion  of  su- 
crose, and,  in  a  more  general  manner,  in  the  decomposition  of 
polysaccharides  such  as  starch  and  dextrine. 

Hydrochloric  acid  is  a  very  active  polymerizing  catalyst  for  alde- 
hydes, whether  it  produces  a  simple  aldolization  with  conservation 
of  the  aldehyde  function  (219),  or  a  cyclization  into  molecules  more 
or  less  condensed  such  as  paraldehyde  (222). 

Sulphuric  acid,  in  small  amounts,  can  likewise  cause  the  change 
of  acetaldehyde  into  paraldehyde  and  also  the  polymerization  of 
ethylene  hydrocarbons  (210). 

Hydriodic  acid,  in  its  capacity  of  a  strong  acid,  can  effect  hy- 
drolyses,  as  do  the  above  acids.  We  may  mention  also  its  use  in  facili- 
tating the  preparation  of  the  mixed  organo-magnesium  halides  from 
chlorides  in  the  Grignard  reaction  (302). 

Nitrous  acid  catalyzes  the  transformation  of  ole'ic  acid  into  its 
isomer,  ela'idic  acid  (186). 

INORGANIC    BASES 

83.  The  alkalies,  and  alkaline  earths,  caustic  potash  and  soda, 
baryta  and  lime,  frequently  act  as  catalysts.    In  inorganic  chemistry 
they  cause  the  rapid  decomposition  of  hydrogen  peroxide  and  hydro- 
gen persulphides. 

43  EMIL  FISCHER,  Berichte,  26,  2400  (1893)  and  27,  615  (1894). 

44  BOESEKEN,  Rec.  Trav.  Chim.  Pays-Bas,  29,  330  (1910). 
46  CBAFTS,  Berichte,  34,  1350  (1901). 


25  ON  CATALYSTS  87 

In  water  solution,  these  strong  bases,  being,  highly  ionized,  hy- 
drolyze  esters  rapidly.  Saponification,  when  carried  out  in  the  pres- 
ence of  excess  of  alkali,  appears,  at  first  sight,  to  be  simply  the  conse- 
quence of  the  formation  of  the  alkali  salt  of  the  acid  of  the  ester,  but, 
in  reality,  the  phenomenon  consists  of  two  successive  phases,  first  the 
hydrolysis  which  liberates  the  acid  and  then  the  neutralization  of  the 
acid  to  form  the  salt. 

Solutions  of  lime  bring  about  rapid  aldolization  of  aldehydes 
(221). 

A  mixture  of  formaldehyde  and  acetaldehyde,  on  long  contact 
with  milk  of  lime,  engenders  a  tetraprimary  erythrol  along  with 
formic  acid.46 

Solid  caustic  potash  causes  the  aldolization  of  acetaldehyde  and 
alcoholic  potash,  the  polymerization  of  isobutyric  aldehyde  (224). 

Caustic  alkalies  frequently  produce  isomerizations  (185). 

FLUORIDES,    CHLORIDES,    BROMIDES, 
AND    IODIDES 

84.  Boron    Fluoride.    Among    fluorides,   that   of    boron   merits 
special  mention.     It  produces  polymerizations  of  hydrocarbons:    one 
part  of  it  is  sufficient  to  polymerize  160  parts  of  oil  of  turpentine.47 

85.  Iodine     Chloride.    The    trichloride     IC13,    the    immediate 
product  of  the  action  of  excess  of  chlorine  on  iodine,  is  a  valuable 
agent  in  the  direct  chlorination  of  organic  compounds  by  gaseous 
chlorine  (278). 

86.  Barium  Chloride.    The  anhydrous  salt  readily  causes  the 
decomposition  of  alkyl  chlorides  into  hydrochloric  acid  and  the  ethy- 
lene  hydrocarbons  (876). 

87.  Aluminum  Chloride.     The  anhydrous  chloride  is  a  catalyst 
of  immense  value.    It  can  be  employed  as  an  agent  in  direct  chlorina- 
tion or  bromination  (284  and  293). 

It  causes  the  direct  fixation  on  benzene,  of  oxygen  (263),  of  sul- 
phur (296) ,  and  of  sulphur  dioxide  (297) . 

It  can  bring  about  the  decomposition  of  alkyl  chlorides  (877)  and 
of  thiophenol  (297). 

In  the  acetylation  of  urea  it  is  a  much  more  active  catalyst  than 
hydrochloric  acid.48 

Anhydrous  aluminum  chloride  is  the  basis  of  a  very  important 

48  TOLLENS  and  WIGAND,  Annalen,  265,  317  (1891). 

47  BERTHELOT,  Ann.  Clrim.  Phys.,  (3),  38,  41  (1853). 

48  BOESEKEN,  Rec.  Trav.  Chim.  Pays-Bos,  29,  330  (1910). 


88  CATALYSIS  IN  ORGANIC  CHEMISTRY  26 

general  method  for  the  condensation  of  organic  compounds,  which  we 
owe  to  Friedel  and  Crafts,49  and  of  which  the  principal  applications 
and  methods  of  operation  will  be  set  forth  in  Chapter  XX. 

It  acts  powerfully  on  hydrocarbons  to  cause  decompositions  as 
well  as  molecular  condensations  (Chapter  XXI). 

88.  Ferric  Chloride.    Anhydrous  ferric  chloride  can  be  substi- 
tuted for  aluminum  chloride  in  many  of  its  catalytic  reactions.    It 
gives  good  results  as  agent  of  direct  chlorination  or  bromination  (285) 
and  even  of  iodination  (295). 

It  can  serve  as  catalyst  in  the  production  of  acetals  (781  and  783). 
It   can  replace   aluminum   chloride   in   the   Friedel    and   Crafts 
synthesis  (899)  as  well  as  in  analogous  condensations  (902). 

89.  Zinc  Chloride.      This  chloride,  having  a  strong  affinity  for 
water,  is  frequently  employed  as  a  dehydrating  agent.     The  reactions 
which  it  produces  are  frequently  considered  as  not  catalytic,  but  a 
closer  examination  classes  them  as  such,  since  they  are  generally  pro- 
duced by  small  amounts  of  the  salt,  smaller  than  would  be  required 
for  a  chemical  reaction. 

Thus  zinc  chloride  is  a  well  defined  catalyst  in  the  acetylation  of 
glycerine  by  acetanhydride  (761),  in  the  crotonization  of  aldehydes 
(795),  and  in  the  formation  of  substituted  indols  by  the  decomposition 
of  phenylhydrazones  (633).  Its  role  is  less  easy  to  define  and  to 
distinguish  from  that  of  an  ordinary  chemical  reagent  in  quite  a 
number  of  reactions,  such  as  the  condensation  of  benzaldehyde  with 
nitromethane,50  with  chloral  hydrate,51  with  ethyl  orthoformate,52  or 
with  phthalic  anhydride,53  or  of  phenols  or  polyphenols  with  aromatic 
amines,54  or  with  fatty  acids.55 

Anhydrous  zinc  chloride  can  replace  aluminum  chloride  in  the 
Friedel  and  Crafts  synthesis  (899),  and  can  also  produce  polymeriza- 
tions (211). 

Chlorides  of  Cobalt,  Nickel,  Cadmium,  and  Lead.  These  de- 
compose alkyl  chlorides  after  the  manner  of  barium  chloride  (876). 

90.  Stannic    Chloride.     In    certain    condensations    of    organic 
molecules  as  of  aliphatic  aldehydes  with  phenols,56  its  role  as  a  cat- 
alyst is  difficult  to  define,  as  has  been  said  of  zinc  chloride,  or  in  the 

49  FRIEDEL  and  CRAFTS,  Ann.  Chim.  Phys.  (6),  i,  489  (1884). 

60  PRIEBS,  Annalen,  225,  321   (1884). 

61  BOESSNECK,  Berichte,  19,  367  (1886). 

62  FISCHER  and  KORNER,  Berichte,  17,  98  (1884). 
83  FISCHER,  Annalen,  206,  86  (1881). 

64  CALM,  Berichte,  16,  2786  (1883). 

65  GOLDZWEIG  and  KAISER,  J.  prakt.  Chem.,  (2),  43,  91  (1891). 
S6  FABINYI,  Berichte,  u,  283  (1878). 


27  ON  CATALYSTS  97 

formation  of  phthalemes  from  phenols  and  phthalic  anhydride,87  but 
it  is  well  established  in  the  addition  of  acid  chlorides  to  ethylene 
hydrocarbons  (241). 

Chlorides  of  Antimony,  Molybdenum,  Thallium  and  Uranium. 
These  can  be  used  as  chlorination  catalysts  (286). 

91.  Cuprous  Chloride,  Bromide,  and  Iodide.    These  cause  the 
decomposition  of  diazonium  salts  with  the  hydracids  into  the  corre- 
sponding aromatic  halogen  compounds,  with  the  elimination  of  nitro- 
gen   (the  Sandmeyer  reaction)    (606).    They   can  bring  about  the 
decomposition  of  phenylhydrazine  (611)  as  well  as  the  production  of 
indols  by  the  decomposition  of  the  phenylhydrazones  (633) .    Cuprous 
chloride    causes    the    scission    of    chlorinated    hydrocarbons    (879). 
Cuprous  iodide  has  been  employed  with  success  in  the  phenylation 
of  primary  aromatic  amines  (901). 

92.  Mercuric   Chloride.    This   accelerates  the   isomerization  of 
isobutyl  bromide  (200)  and  permits  acetaldehyde  to  be  prepared  by 
the  hydration  of  acetylene   (309). 

93.  Aluminum  Bromide.     This  is  advantageously  employed  as 
catalyst  in  bromination.    It  causes  rapid  transformation  of  propyl 
bromide  into  the  isomeric  isopropyl  bromide  (199). 

94.  Potassium  Iodide.     Organic  chlorine  derivatives  usually  re- 
act with  less  facility  than  the  corresponding  iodides.    Their  action 
can  be  greatly  facilitated  by  the  addition  of  10%  potassium  iodide, 
which    apparently    permits   the    progressive   transformation    of   the 
chloride  into  the  more  reactive  iodide.58 

95.  Potassium  Cyanide.    It  acts  as  an  efficient  catalyst  of  aldo- 
lization  (220)  and  even  of  polymerization  in  the  strict  sense  (230). 

The  double  cyanide  of  potassium  and  copper  has  been  employed 
as  oxidation  catalyst  (268). 

INORGANIC    SALTS    OF    OXYGEN   ACIDS 

96.  A  large  number  of  these  salts  can  act  as  catalysts  in  organic 
reactions. 

Salts  formed  from  weak  acids  or  from  weak  bases  or  ammonia, 
readily  separated  by  dissociation,  usually  show  effects  which  could 
be  produced  by  their  constituents  separately. 

97.  Alkaline  Carbonates.    These  may  be  used  advantageously 
in  place  of  caustic  potash  in  reactions  of  aldolization  or  of  analogous 
condensations  (219  and  236). 

57  BAEYER,  Annalen,  202,  154  (1880). 

58  WOHL,  Berichte,  39,  1951  (1906). 


98  CATALYSIS  IN  ORGANIC  CHEMISTRY  28 

Potassium  Bisulphate.  This  salt  can  act  as  free  sulphuric  acid, 
either  in  esterification  or  in  the  direct  production  of  acetals,  or  in 
condensations  effected  with  elimination  of  water  such  as  that  of 
dimethyl  aniline  with  benzaldehyde.69 

Ammonium  Sulphate,  Nitrate,  and  Chloride.  These  can  act  as 
the  free  acids  in  esterification,  or  in  analogous  reactions,  such  as  the 
production  of  acetals  (783). 

98.  Barium  and  Calcium  Carbonates.    These  are  equivalent  to 
the  free  oxides. 

Calcium  Sulphate.  Either  as  the  hydrate,  or  dehydrated  below 
400°,  it  possesses  a  certain  activity  for  dehydrating  alcohols  into  the 
ethylene  hydrocarbons  (718). 

99.  Aluminum  Sulphate  and  Phosphate.    These  are  dehydra- 
tion catalysts  analogous  to  free  alumina  (718). 

Silicates.  Clay  and  kaolin,  hydrated  silicates  of  aluminum, 
catalyze  the  dehydration  of  alcohols  as  does  alumina  (717). 

Broken  glass,  which  is  a  mixed  silicate  of  variable  composition, 
has  properties  which  vary  with  this  composition.  In  the  decomposi- 
tion of  formic  acid  around  300°,  Jena  glass  yields  mainly  carbon  di- 
oxide and  hydrogen,  while  the  ordinary  white  glass  gives  water  and 
carbon  monoxide,  approaching  pure  silica  (828). 

Pumice,  in  spite  of  its  porous  structure,  is  only  slightly  active  as 
a  catalyst  and  approaches  silica  in  its  action. 

100.  Ferrous  and  Manganous  Salts.    In  the  presence  of  water, 
these  are  active  oxidation  catalysts    (264).    Thus  the  presence  of 
various  manganous  salts  aids  the  oxidation  of  oxalic  acid  solutions.60 

101.  Magnesium  Sulphate.    This  is  an  excellent  catalyst  for  the 
dehydration  of  glycerine  into  acrole'in  (725). 

102.  Mercuric    Sulphate.     This    can    cause    the    hydration    of 
acetylene  hydrocarbons  into  ketones  (309),  and  the  oxidation  of  or- 
ganic  compounds  by   fuming  sulphuric  acids    (272).    Its  presence 
determines  the  nature  of  the  isomers  produced  in  the  direct  sulphona- 
tion  of  aromatic  molecules  (816).    It  can  also  determine  isomeriza- 
tions  (195). 

103.  Copper  Sulphate.    In  Deacon'^  process,  it  is  copper  sulphate 
that  catalyzes  the  oxidation  of  hydrochloric  acid  by  air  at  430°  with 
the  production  of  chlorine.    It  can,  although  with  disadvantage,  re- 
place mercuric  sulphate  in  the  oxidation  of  organic  compounds  by 
fuming  sulphuric  acid  (272). 

69  WALLACE  and  WUSTEN,  Berichte,  16,  149  (1883). 

60  JOBISSBN  and  REICHER,  Zeit.  physik.  Chem.,  31,  142  (1900). 


29  ON  CATALYSTS  107 

VARIOUS    COMPOUNDS 

104.  Ammonia.     The  presence  of  ammonia  favors  the  polymeriza- 
tion of  cyanamide  (233). 

Amines.  Aliphatic  primary  and  secondary  amines  are  of  use  as 
catalysts  in  the  complex  reactions  in  the  vulcanization  of  rubber. 
Piperidine  has  been  suggested  for  the  purpose.61  Nitrosodimethyl- 
aniline  has  been  recommended  in  the  ratio  of  0.3  to  0.5  part  to  100 
parts  caoutchouc  and  10  parts  sulphur  at  140°. 62 

Alkyl  Halides  and  Esters.  A  small  quantity  of  an  alkyl  iodide, 
especially  methyl  or  ethyl  iodide,  greatly  facilitates  the  preparation 
of  the  organo-magnesium  compounds  in  the  Grignard  reaction,  par- 
ticularly when  chlorides  are  used  (302). 

Acetaldehyde,  heated  to  100°  with  ethyl  iodide,  condenses  to  par- 
aldehyde.63 

Ethyl  oxalate,  by  its  presence,  favors  the  reduction  of  ethylene 
bromide  to  ethyl  bromide  by  the  alloy  of  sodium  and  zinc.64 

Ethyl  nitrite,  in  alcohol  solution,  causes  the  transformation  of 
thiourea  into  ammonium  isosulphocyanate. 

Ethers.  Ethyl  ether,  as  well  as  amyl  ether,  and  anisol, 
C6H5.O.CH3,  plays  an  important  role  as  catalyst  in  the  formation  of 
the  organo-magnesium  complexes  in  the  Grignard  reaction  (300). 

105.  Aldehydes.    Acetaldehyde  provokes  the  hydration  of  cyan- 
ogen to  oxamide  (311). 

106.  Organic  Acids.    Acetic  acid  can  sometimes  act,  after  the 
fashion  of  mineral  acids,  to  cause  combinations  with  elimination  of 
water,  as  in  the  production  of  acetals  (780).    Its  catalytic  role  can 
be  disputed  in  the  condensation  of  benzaldehyde  with  malonic  acid.65 

Isoprene  heated  with  acetic  acid  is  transformed  into  artificial 
rubber  (215). 

Oxalic  acid  acts  like  hydrochloric  or  phosphoric  acid  in  the  poly- 
merization of  aldehydes. 

107.  Alkaline  Acetates.    Sodium  acetate  is  a  quite  active  dehy- 
dration catalyst.    It  produces  the  crotonization  of  aldehydes  (795) 
as  well  as  their  simple  polymerization.    It  is  employed  as  a  catalyst 
to  aid  in  the  esterification  of  alcohols  by  acetanhydride. 

Quite  a  large  number  of  organic  condensations,  which  take  place 

61  BAYER  &  Co.,  German  Patent,  265,221  (1912),  C.  1913,  (2),  1444. 

62  PEACHEY,  English  Patent,  4,263  of  1914. 

63  LIEBEN,  Annalen,  SuppL,  i,  114  (1861). 

64  MICHAEL,  Am.  Chem.  J.,  25,  419  (1901). 

65  CLAISEN  and  CRISMER,  Annalen,  218,  155  (1883). 


108  CATALYSIS  IN  ORGANIC  CHEMISTRY  30 

with  elimination  of  water,  have  as  their  basis  the  use  of  sodium  ace- 
tate, but  it  is  usually  employed  in  such  large  proportions  that  its 
catalytic  role  is  masked.  This  is  the  case  in  the  condensation  of 
phthalid  with  phthalic  anhydride  to  form  diphthalid.66 

Likewise  potassium  acetate  permits  the  condensation  of  acetic  acid 
with  phthalic  anhydride  to  form  phthalylacetic  acid.67 

It  is  under  the  same  conditions  —  that  is,  employed  in  large  quan- 
tity—  that  sodium  acetate  causes  acetanhydride  to  act  on  benzalde- 
hyde  to  form  cinnamic  acid  in  Perkin's  synthesis.68 

108.  Nitroso   Compounds.     The  nitroso  derivatives  of  methyl- 
aniline,  dimethylaniline,  and  diphenylamine  are  accelerators  in  the 
vulcanization  of  caoutchouc.    The  same  property  belongs  to  nitroso- 
phenol  and  nitrosonaphthol  but  not  to  the  isomeric  nitrosoamines.69 

109.  Alkyl  Cyanides.    Methyl  and  ethyl  cyanides  are  active  cat- 
alysts in  the  reaction  of  sodium  with  alkyl  iodides,  or  with  similar 
compounds  (605). 

110.  Fibrine.     It  may  be  recalled  that  fibrine  catalytically  de- 
composes hydrogen  peroxide  very  rapidly. 

DURATION    OF   THE    ACTION    OF    CATALYSTS 

111.  It  would  seem,  by  definition,  that  the  action  of  catalysts 
should  be  prolonged  indefinitely,  and  this  perpetuity  would  be  assured 
to  them  if  they  did  not  suffer  any  alteration  in  the  course  of  the  re- 
actions which  they  effect.     If  any  change  does  take  place,  as  is  most 
frequently  the  case  with  solid  catalysts  acting  in  gaseous  or  liquid 
media,  an  alteration  of  the  surface,  even  slight,  brings  on  progressive 
diminution  of  activity  which  may  go  as  far  as  total  suppression. 

In  hydrogenations  carried  on  by  nickel  in  gaseous  systems,  using 
pure  and  sufficiently  volatile  substances  and  thoroughly  purified  hy- 
drogen, at  a  carefully  regulated  temperature,  the  action  can  be  con- 
tinued by  the  same  metal  a  very  long  time  without  appreciable 
weakening.  Sabatier  and  Senderens  were  able  to  effect  the  trans- 
formation of  benzene  into  cyclohexane  for  more  than  a  month  with 
the  same  nickel,  the  operation  being  interrupted  every  evening  and 
resumed  in  the  morning.  The  slight  oxidation  which  the  metal  suf- 
fered over  night,  in  the  cold  tube,  caused  no  inconvenience  because 
the  oxide  was  again  reduced  by  the  hydrogen  at  the  beginning  of  the 
next  run.70 

66  GRAEBE  and  GUYE,  Annalen,  233,  241  (1886). 

67  GABRIEL  and  NEUMANN,  Berichte,  26,  925-  (1893). 
es  PKRKIN,  J.  Chem.  Soc.,  31,  388  (1877). 

69  PEACHBY,  J.  Soc.  Chem.  Ind.,  36,  424  (1917). 

70  SABATIEB  and  SENDERENS,  Ann.  Chim.  Phys.,  (8),  4,  334  (1905). 


31  ON  CATALYSTS  114 

112.  Poisoning  of  Catalysts.    On  the  contrary,  traces  of  chlorine, 
bromine,  iodine  and  sulphur  in  the  system  are  frequently  sufficient 
to  suppress  the  activity  of  the  nickel  entirely.    It  appears  to  be 
poisoned.    Benzene  which  is  not  absolutely  free  from  thiophene  can 
not  be  hydrogenated.    An  infinitely   small   amount   of   bromine  in 
phenol  renders  it  incapable  of  being  changed   into   cyclohexanol.71 
Chlorine  or  bromine  derivatives  of  benzene  have  never  been  hydro- 
genated since  the  first  portions  of  these  compounds  alter  the  metal 
immediately  in  an  irremediable  manner. 

113.  But  the  conditions  under  which  this  poisoning  of  the  metal 
take  place  are  quite  complex.    The  presence  of  free  halogens  or  halo- 
gen acids  in  the  hydrogen  is  much  less  harmful  than  the  presence  of 
combined  halogen  in  the  vapors  submitted  to  hydrogenation.    This 
has  been  observed  by  Sabatier  and  Espil  in  the  hydrogenation  of 
benzene.72 

In  an  apparatus  in  which  the  hydrogenation  of  benzene  was  pro- 
gressing regularly  over  nickel  at  180°,  the  benzene  was  replaced  by 
benzene  containing  0.5%  iodine.  The  hydrogenation  continued  for 
several  hours  with  an  excellent  yield.  The  escaping  hydrogen,  after 
the  condensation  of  the  cyclohexane,  disengaged  abundant  fumes  of 
hydriodic  acid  showing  that  the  iodine  had  been  hydrogenated  by  the 
catalyst.  The  operation  was  interrupted  after  130  g.  of  cyclohexane 
had  been  collected  and  it  was  found  that  the  nickel  had  combined 
with  iodine  in  the  first  half  only  of  the  tube.  This  half  was  incapable 
of  carrying  on  the  hydrogenation  but  the  other  half  was  unhurt.  The 
poisoning  of  the  metal  by  the  iodine  had  taken  place  only  slowly  and 
step  by  step;  the  hydriodic  acid  had  had,  on  its  own  account,  no 
harmful  effect  and  had  not  converted  into  the  iodide  the  metal  the 
surface  of  which  was  covered  with  an  unstable  hydride  which  pro- 
duced the  hydrogenation  (167).  Doubtless  the  fixation  of  the  hydro- 
gen on  the  iodine  and  the  benzene  in  contact  with  the  nickel  is  much 
more  rapid  than  the  reaction  of  the  nickel  with  the  iodine  or  with  the 
hydriodic  acid.  As  in  the  direct  hydrogenation  of  unsaturated  hydro- 
carbons (422) ,  the  metal  protects  itself,  by  its  own  action,  against  the 
permanent  alteration  which  would  render  it  inactive. 

114.  Similar  results  have  been  obtained,  by  the  same  authors,  in 
hydrogenating  benzene  with  hydrogen  containing  hydrogen  chloride, 
but  if  traces  of  brombenzene  or  chlorbenzene  are  added  to  the  ben- 
zene, the  production  of  cyclohexane  ceases  almost  immediately  and 
the  nickel  is  incapable  of  regaining  its  activity. 

71  SABATIER  and  MAILHE,  Compt.  rend.,  153,  160  (1911). 

72  SABATIER  and  ESPIL,  Bull  Soc.  Chim.,  (4),  15,  778  (1914). 


115  CATALYSIS  IN  ORGANIC  CHEMISTRY  32 

It  is  plain  that  free  chlorine  or  bromine  in  the  hydrogen,  unlike 
iodine,  would  produce  a  definite  poisoning  of  the  metal  since  they 
would  offer  the  possibility  of  direct  substitution  in  the  benzene  which 
iodine  does  not  do. 

Sabatier  and  Espil  have  likewise  been  able,  for  several  hours,  to 
transform  into  cyclohexane  benzene  containing  10%  of  carbon  disul- 
phide,  but  traces  of  thiophene  added  to  the  benzene  stopped  the  re- 
action at  once. 

115.  The  use  in  the  oil  industry  (937  et  seq.)  of  nickel  as  hydro- 
genation  catalyst  suspended  in  the  liquid,  has  led  to  the  determina- 
tion of  the  greater  or  less  toxicity  of  a  number  of  substances  which 
may  be  present  in  small  amounts  in  the  oils  to  be  treated. 

The  soaps  formed  from  the  various  metals  or  oxides  are,  from  this 
point  of  view,  very  dissimilar:  while  those  of  nickel,  thorium,  cerium, 
aluminum,  and  calcium  are  absolutely  without  harmful  effect,  those 
of  potassium,  barium,  zinc,  cadmium,  lead,  and  uranium  are  harmful. 

The  nickel  salts  of  organic  monobasic  acids,  as  well  as  of  lactic, 
oxalic,  and  succinic  acids,  are  without  effect.  The  same  can  be  said 
of  the  free  fatty  acids  such  as  acetic  and  stearic,  but  oxystearic,  malic, 
tartaric  and  citric  acids  are  true  poisons  for  the  nickel  catalyst. 
Toxicity  is  also  shown  by  calcium  hydroxide,  potash,  boric  acid,  am- 
monium molybdate,  as  well  as  by  sulphur,  selenium,  red  phosphorus, 
glycerine,  lecithine,  morphine,  strychnine,  amygdaline,  and  cyanides. 
Tin  and  aluminum  in  powder  are  without  action,  but  iron,  lead,  and 
zinc  are  harmful.73 

116.  With  a  platinum  catalyst,  the  extreme  toxicity  of  compounds 
of  sulphur,74  phosphorus  and  arsenic  and  of  cyanides,  etc.,  has  long 
been  known.    The  activity  of  colloidal  platinum  is  diminished  or 
destroyed  by  a  large  number  of  materials.     Their  toxicity  has  been 
measured  by  means  of  the  velocities  of  decomposition  of  hydrogen 
peroxide  and  it  has  been  suggested  to  designate  by  the  term  toxicity, 
the  dilution   (in  liters  per  gram-molecule)   at  which  the  velocity  of 
decomposition  in  contact  with  0.000,01   gram-atom  of  platinum,  is 
reduced  one-half.75 

Among  the  violent  poisons,  hydrocyanic  acid  stands  at  the  head 
with  toxicity  21,000,000,  followed  by  iodine  with  7,000,000,  mercuric 
chloride  with  2,500,000,  sodium  hyposulphite,  carbon  disulphide,  car- 
bon monoxide,  and  phosphorus.  Among  the  moderate  poisons,  are 
placed  aniline  with  toxicity,  30,000,  bromine  with  23,000,  hydrochloric 

73  SEIICHIDENO,  J.  Chem.  Ind.,  Tokyo,  21,  898  (1918). 

74  TURNER,  Pogg.  Ann.,  2,  210  (1824). 

78  BREDIQ  and  IKEDA,  Zeit.  phys.  Chem.,  37,  1  (1901). 


33  ON  CATALYSTS  119 

acid  with  3,100,  oxalic  acid,  amyl  nitrite,  arsenious  acid,  and  ammo- 
nium chloride.  Among  the  feeble  poisons,  are  found  phosphorus 
acid,  900,  sodium  nitrite,  and  hydrofluoric  acid,  while  potassium 
chlorate,  alcohol,  ether  and  pinene  have  no  toxicity  and  formic  acid, 
hydrazine,  and  dilute  nitric  acid  are  rather  favorable.  These  toxicity 
coefficients  would  certainly  be  very  different  if  measured  with 
platinum  black  or  sponge.76 

117.  Platinum  black  is  very  sensitive  to  the  poisons  enumerated 
for  colloidal  platinum.    Traces  of  potassium  cyanide  are  sufficient  to 
take  from  the  metal  all  power  to  hydrogenate  the  aromatic  nucleus, 
and  also  to  weaken  greatly  the  hydrogenation  of  ethylene  bonds.77 

Contrary  to  what  has  been  said  about  colloidal  platinum,  the 
hydrogenation  velocity  of  pinene  is  diminished  if  it  is  dissolved  in 
alcohol  or  in  any  substance  capable  of  furnishing  alcohol  e.  g.  ether 
or  ethyl  acetate.  The  fatty  acids  have  little  action,  except  formic, 
which  has  a  marked  toxic  effect.78 

118.  The  Fouling  of  Catalysts.    Other  causes  of  alteration  can 
come  in  to  bring  on  the  decline  of  catalysts.    It  happens  quite  fre- 
quently that,  along  with  the  principal  reaction,  there  are  side  reactions 
which  become  more  important  at  elevated  temperatures  and  which 
give  rise  to   highly   condensed  substances  which   are   only   slightly 
volatile,  carbonaceous  or  tarry.    Such  substances  are  slowly  deposited 
on  the  active  surfaces  where  they  hinder  the  contact  with  the  gas, 
rendering  the  useful  reaction  slow. 

In  hydrogenations,  or  decompositions  by  finely  divided  metals,  the 
more  active  the  metals,  the  more  rapid  are  formations  of  this  sort. 
The  most  fiery  catalysts  are  the  most  rapidly  enfeebled. 

The  decline  of  a  catalyst,  either  from  poisoning  or  fouling,  is  indi- 
cated by  the  diminishing  of  the  yields  in  the  reaction  which  it 
catalyzes. 

When  a  fatigued  nickel  catalyst  is  dissolved  in  dilute  hydrochloric 
acid,  fetid  hydrocarbons  are  evolved  with  the  hydrogen  and  brown 
carbonaceous  or  viscous  materials  are  deposited. 

119.  It  can  be  seen  that  an  analogous  enfeeblement  will  take  place 
when  the  reaction  produces  a  material  which  is  only  slightly  volatile 
at  the  temperature  of  the  tube  and  which  impregnates  the  metal  more 
or  less  rapidly  thus  opposing  its  regular  activity.    This  takes  place 
in  the  hydrogenation  of  aniline  in  the  presence  of  nickel  at  190°,  since 

76  See  comprehensive  article  by  BANCROFT  J.  Phys.  Chem.,  21,  767  (1917). 

77  MADINAVEITIA,  Soc.  Espan.  Phys.  Chim.,  u,  328  (1913). 

78  BOESEKKN,  VAN  DEB  WEiDE  and  MOM,  Rev.  Trav.  Chim.  Pays-Bos,  35, 
260   (1916). 


120  CATALYSIS  IN  ORGANIC  CHEMISTRY  34 

there  is  produced,  in  addition  to  the  cyclohexyl  amine  boiling  at  134°, 
two  other  amines  which  are  only  slightly  volatile,  dicyclohexyl  amine 
and  cyclohexyl  aniline,  which  boiling  above  250°,  are  carried  off  with 
difficulty  by  the  hydrogen  and  remain  partly  in  the  liquid  form  in 
contact  with  the  metal. 

120.  It  is  to  avoid  analogous  effects  that  it  is  necessary  to  watch 
that  the  metal  is  never  wetted  by  an  excessive  flow  of  the  liquid  which 
is  being  used  or  in  consequence  of  an  accidental  lowering  of  the  tem- 
perature  of  the  tube.     In  the  preparation   of   cyclohexanol   or   its 
homologs  by  the  hydrogenation  of  phenol  or  the  cresols,  the  reaction 
is  carried  on  at  a  temperature  only  a  little  above  the  boiling  points 
of  the  liquids  and  it  happens  sometimes  that  the  nickel  is  wetted  by 
the  liquid.     The  catalyst  immediately  becomes  nearly  inactive,  be- 
cause the  surface  is,  without  doubt,  altered  permanently  by  contact 
with  the  liquid  phenol  or  cresol. 

121.  Catalytic  hydrogenation  by  finely  divided  metals  is,  to  a 
certain  extent,  comparable  to  the  action  of  the  figured  ferments.79 
As  with  these,  there  are  three  periods,  an  initial  period  in  which  the 
catalyst  adapts  itself  to  its  function,  a  period  of  normal  activity  and 
a  period  of  decline,  ending  in  the  death  of  the  ferment. 

The  first  period  is  a  variable  state  and  is  usually  of  short  dura- 
tion: it  corresponds,  without  doubt,  to  the  superficial  modification 
which  the  metal  undergoes  when  the  atmosphere  of  pure  hydrogen 
which  surrounded  it,  is  replaced  by  a  mixture  of  the  vapors  with 
hydrogen. 

The  second  period,  that  of  normal  functioning,  is  usually  very  long 
and  would  be  indefinite  unless  something  is  passed  in  or  is  produced 
which  can  alter  the  surface  of  the  metal.  Such  substances  may  enter 
with  the  hydrogen  or  with  the  substance  to  be  hydrogenated  or  may 
be  produced  in  the  reaction. 

122.  Catalytic  oxides,  although  less  sensitive  than  the  metals  to 
chemical  alterations  of  their  surfaces,  may,  nevertheless,  suffer  from 
this  cause  notable  diminution  of  activity  even  to  complete  suppres- 
sion of  their  function.     In  many  cases  they  are  so  fouled  that  they 
are  weakened  or  paralyzed. 

123.  Regeneration  of  altered  Catalysts.     In  so  far  as  the  alter- 
ation of  metallic  catalysts  is  due  simply  to  fouling  by  deposits  of 
carbon  or  of  tarry  substances,  calcination  in  a  current  of  air  is  suf- 

79  « Figured  ferments  "  is  an  obsolete  expression  for  "  organized  ferments,'1 
meaning  ferments  in  which  cells  can  be  found  with  the  microscope,  as  in  the 
yeasts;  in  contradistinction  to  such  ferments  as  saliva,  etc.  The  cells  were 
spoken  of  as  "figures,"  hence  "figured  ferments."  —  H.  S.  JENNINGS. 


35  ON  CATALYSTS  126 

ficient  to  burn  off  these  substances,  converting  the  metal  (nickel,  iron, 
copper)  into  the  oxide  which  a  new  reduction,  carried  out  at  a  suitable 
temperature,  will  reconvert  to  the  metal.  These  operations  can  be 
carried  out  in  turn  in  the  tube  itself  in  which  the  catalysis  takes 
place. 

This  procedure  is  not  suitable  for  platinum  black,  which  by  being 
heated  to  redness  loses  nearly  all  of  its  catalytic  activity  (63). 

It  does  not  serve  well  for  the  greater  part  of  the  metal  oxides  which 
are  greatly  diminished  in  activity  by  heating  to  a  high  temperature; 
but  it  does  serve  well  for  thoria  which  has  been  fouled  by  long  use 
(708). 

124.  Metallic  catalysts  poisoned  by  vapors  of  chlorine,  bromine, 
iodine,  sulphur,  etc.,  are  difficult  to  revivify  except  by  dissolving  in 
a  suitable  acid  and  working  over  completely. 

Calcination  does  not  remove  chlorine  from  slightly  chlorinated 
nickel.  The  action  of  hydrogen  reduces  the  chloride  to  the  metallic 
state  below  400°,  but  the  resulting  metal  is  in  a  peculiar  fibrous  state 
and  is  incapable  of  reducing  benzene  to  cyclohexane.  Even  after 
oxidation  and  a  second  reduction  it  is  a  poor  catalyst. 

125.  It  can  be  slowly  restored  to  complete  activity  by  employing 
it  for  some  time  in  the  reduction  of  nitrobenzene  to  aniline,  work 
which  poisoned  nickel  is  still  capable  of  doing.    The  aniline  which  is 
produced  contains  increasing  amounts  of   cyclohexyl   amine.    After 
some  hours  of  this  treatment  the  power  of  the  metal  to  produce  cyclo- 
hexane from  benzene  is  completely  restored.    On  the  contrary,  poison- 
ing by  bromine  or  iodine  seems  to  resist  this  treatment.80 

MIXTURE    OF    CATALYSTS    WITH    INERT 
MATERIALS 

126.  The  desire  to  increase  the  active  surface  of  solid  catalysts 
had  led  to  disseminating  them  over  inert  porous  materials  such  as 
pumice,   asbestos,   infusorial   earth,   and  various  metal   salts.    This 
practice  has  appeared  specially  advantageous  for  expensive  catalysts 
such  as  platinum  and  palladium.    Thus  in  the  manufacture  of  sul- 
phuric acid  by  the  contact  process,  the  catalytic  masses  are  either 
platinized  asbestos,  or  anhydrous  magnesium  sulphate  impregnated 
with  platinum  (about  14  g.  metal  per  kilogram  of  sulphate). 

Nickeled  pumice  which  has  been  employed  by  certain  chemists  in 
place  of  nickel  powder  for  hydrogenations,  is  readily  prepared  by 
incorporating  the  crushed  pumice  in  a  thick  paste  of  precipitated 

80  SABATIEE  and  ESPIL,  Bull.  Soc.  Chim.,  (4),  15,  779  (1914). 


127  CATALYSIS  IN  ORGANIC  CHEMISTRY  36 

nickel  hydroxide,  drying  in  the  oven,  and  finally  reducing  in  the  tube 
that  is  to  be  used  for  the  hydrogenations.81 

127.  In  the  case  of  catalytic  metals  which  have  to  be  carried  to  a 
red  heat  (932),  the  use  of  inert  siliceous  carriers  may  have  serious 
consequences  owing  to  the  formation  of  silicates  which  may  suppress 
the  activity  of  the  metal.    In  such  cases  it  is  best  to  use  carriers  free 
from  silica,  such  as  magnesia,  alumina,  natural  bauxite,  lime  or  car- 
bonate of   calcium,   etc.,  either  by   employing  these   substances   in 
powders  intimately  mixed  with  the  oxides,  the  reduction  of  which  is 
to  furnish  the  metals,  or  by  previously  sticking  together  these  mixtures 
in  little  lumps  with  the  aid  of  non-siliceous  materials  (Sabatier  and 
Mailhe). 

128.  In  certain  cases  the  use  of  inert  supports  for  solid  catalysts 
can  lead  to  serious  trouble.    When  the  catalyst  is  to  be  heated  on  a 
furnace,  it  is  disposed  in  a  thin  layer  in  the  tube.    By  a  fear  entirely 
unjustified,  in  view  of  the  great  velocity  of  diffusion  of  hot  gases, 
some  have  doubted  the  sufficiency  of  the  contact  between  the  gas, 
circulating  too  freely  in  the  upper  part  of  the  tube,  and  the  catalyst. 
Guided  by  this  thought,  the  whole  height  of  the  tube  has  been  filled 
with  the  pumice  impregnated  with  the  catalyst.    But  these  conditions 
are  not  favorable,  since  the  temperature  varies  much  from  bottom  to 
top  of  the  tube.     On  the  contrary,  filling  the  tube  entirely  with  the 
catalytic  mass  presents  no  inconvenience  when  the  tube  is  heated  all 
around  as,  for  example,  by  an  electric  resistance  wound  around  it. 

si  BRUNEL,  Ann.  Chim.  Phys.,  (8),  6,  205  (1905). 


CHAPTER   III 
THE    MECHANISM    OF    CATALYSIS 

129.  The  extreme  diversity  of  catalytic  reactions  makes  it  evident 
that  difficulties  will  be  encountered  in  giving  an  explanation  that  will 
fit  all  cases. 

Berzelius,  who  was  the  first  to  define  catalytic  phenomena  and 
to  give  them  this  name  (4)  did  not  really  furnish  any  explanation 
for  them  and  found  only  vague  terms  with  which  to  characterize  the 
catalytic  force  which  he  regarded  as  the  cause  of  reactions  of  this 
kind.  "  It  is  evident,"  said  he,  "  that  the  catalytic  force  acts  princi- 
pally by  means  of  the  polarity  of  the  atoms  which  it  augments, 
diminishes  or  changes.  In  other  words,  the  catalytic  force  manifests 
itself  by  the  excitation  of  electrical  relations  which,  up  to  the  present, 
have  escaped  our  investigation."1  And  he  adds:  "  From  all  that 
precedes,  it  follows  necessarily  that  the  sources  of  power  (light,  heat, 
electricity)  contain  the  cause  of  the  activity  of  matter,  which,  without 
their  influence,  would  be  inert  and  in  a  state  of  unalterable  and  eternal 
repose." 

To  the  mind  of  Berzelius,  catalytic  forces  are  then  of  the  order  of 
the  sources  of  power  "  different  effects  of  one  first  cause  which,  under 
definite  circumstances,  pass  from  one  modification  into  another."2 
But  their  nature  remains  no  less  mysterious:  the  calorific  phenomena, 
sometimes  intense,  which  frequently  accompany  catalyses,  may  be 
the  consequences  rather  than  the  determining  cause. 

130.  In  a  great  number  of  catalyses,  such  as  are  realized  by  plati- 
num black  and  by  finely  divided  metals  prepared  by  reduction  of 
oxides,  the  porous  state  seems,  at  least  at  first  sight,  to  be  the  deter- 
mining cause  of  the  catalytic  activity  and  this  thought  is  the  basis  of 
the  explanation  that  has  been  given  of  the  mechanism  of  catalysis 
and  which,  accepted  readily  by  many  chemists,  has  been  usually 
elaborated  in  treatises. 

1  BERZELIUS,  Traite  de  Chemie,  2nd  Ed.,  Paris,  1845,  I,  112. 

2  BERZELIUS,  loc.  cit.,  36. 


37 


131  CATALYSIS  IN  ORGANIC  CHEMISTRY  38 

PHYSICAL   THEORY    OF    CATALYSIS 

131.  Porous  materials,  whose  surfaces  are  very  large  as  compared 
with  their  masses,  enjoy  the  property  of  absorbing  gases  with  more 
or  less  energy.    A  case  of  the  absorption  of  gases  by  solids,  that  has 
been  much  studied,  is  that  of  wood  charcoal. 

When  1.57  g.  coconut  charcoal,  corresponding  to  1  cc.  of  compact 
carbon,  has  been  heated  to  redness  and  cooled  under  mercury,  it  ab- 
sorbs in  the  cold  (at  15°  and  760  mm.)  quite  various  volumes  of  gases, 
all  the  way  from  2  cc.  for  argon  to  178  cc.  for  ammonia.  These 
volumes  increase  nearly  proportionally  with  pressure  and  decrease 
greatly  when  the  temperature  is  raised. 

The  volume  mentioned  above  for  ammonia  shows  that  this  gas, 
if  compressed  to  a  volume  equal  to  the  total  volume  of  the  charcoal 
would  require  a  pressure  of  178  atmospheres,  and  as  this  gas  is  lique- 
fied at  15°  under  5.5  atmospheres,  it  is  necessary  to  assume  that  the 
ammonia  exists  in  the  pores  of  the  charcoal  in  the  liquid  condition, 
in  which  it  would  occupy  a  volume  of  about  0.2  cc.  (from  the  known 
density  of  liquid  ammonia). 

The  absorption  of  the  gas  by  the  carbon  liberates  much  heat  and 
this  amount  of  heat  is  even  larger  than  that  obtained  by  the  lique- 
faction of  the  gas.  Thus  the  amounts  of  heat  per  cubic  centimeter 
of  gas  are:  8 

Absorption  by 

carbon  Liquefaction 

Sulphur  dioxide  0.61  to  0.47  cal.  0.26  cal. 

Ammonia     0.45  to  0.33  cal.  0.20  cal. 

For  ammonia,  the  heat  of  absorption  is  little  different  from  the 
heat  of  solution  in  water  and  is  much  larger  than  the  heat  of  solution 
in  the  case  of  sulphur  dioxide.4 

For  hydrogen,  the  heat  of  absorption  by  carbon  is  six  times  the 
heat  of  liquefaction  (Dewar). 

132.  To  explain  these  singular  phenomena,  it  is  assumed  that  the 
enormous  attraction  of  the  surface  of  the  cavities  of  the  wood  char- 
coal causes  the  accumulation  of  the  gases  in  the  cavities,  at  pressures 
which  are  not  very  great  for  the  permanent  gases  (argon,  hydrogen, 
nitrogen),  however,  exceeding  35  atmospheres  for  oxygen,  but  which 
are  very  high  for  the  easily  liquefiable  gases,  generally  much  greater 

8  FAVRB  and  SILBERMANN,  Ann.  Chim.  Phys.,  (3),  37,  465  (1853).  REGNAULT, 
Ibid.,  (4),  24,  247  (1871). 

4  LE  CHATEIJER,  Lemons  sur  le  Carbone,  Paris,  1908,  p.  133. 


39  THE  MECHANISM  OF  CATALYSIS  135 

than  the  pressures  required  for  liquefaction:  this  liquefaction  would 
be  actually  accompanied  by  a  strong  compression  of  the  thin  layer 
of  liquid  produced  on  the  carbon  walls.  This  compression  would  be 
responsible  for  the  excess  of  the  heat  of  absorption  over  that  of 
liquefaction. 

133.  An  analogous  evolution  of  heat  has  been  observed  when  any 
liquid  whatever  is  absorbed  by  a  solid  having  a  very  large  surface, 
such  as  a  fine  powder,  and  is  called  heat  of  imbibition. 

Powdered  quartz,  with  grains  averaging  0.005  mm.  diameter, 
disengages  per  gram,  when  wetted: 

With  water  14  calories 

With  benzene     4        " 

Calculating  the  surface  of  the  grains,  the  heat  of  wetting  by  water 
appears  to  be  0.00105  cal.  for  1  sq.  cm.  of  quartz  at  7°. 

It  has  been  shown  likewise,  that  the  wetting  by  water  of  1  g. 
starch  evolves  22  calories,  1  g.  wood  charcoal,  7  calories,  1  g.  alumina, 
2  calories. 

134.  The  absorption  of  gases  in  the  pores  of  the  carbon  is  equiva- 
lent to  compressing  the  gases  to  a  greater  or  less  pressure.    Simul- 
taneously there  is  the  liberation  of  considerable  heat  by  the  absorp- 
tion.   It  is  imagined  that  the  heat  and  pressure  cause  reactions  to 
take  place.    Hydrogen  and  chlorine  may  unite  in  the  cold  when  they 
meet  each  other  thus  in  the  pores  of  the  carbon,  and  it  is  the  same 
way  with  carbon  monoxide  and  chlorine  and  with  hydrogen  sulphide 
and  oxygen. 

The  oxygen  which  is  absorbed  combines  little  by  little  with  the 
carbon  in  the  cold  to  give  carbon  dioxide.  When  the  gases  are 
pumped  out  of  wood  charcoal,  which  has  been  exposed  to  air,  scarcely 
anything  is  obtained  except  nitrogen  and  carbon  dioxide. 

It  would  seem  then  that  porous  carbon  should  be  a  universal  cat- 
alyst for  all  gas  reactions,  lowering  the  reaction  temperatures  greatly. 
However,  except  for  the  formation  of  carbonyl  chloride  (282) ,  carbon 
is  a  mediocre  catalyst  and  of  little  use,  doubtless  because  gaseous 
interchanges  do  not  take  place  rapidly  enough  in  it. 

135.  Various  powdered  substances  have  greater  or  less  power  of 
absorbing  gases,  but  generally,  especially  for  oxides  and  salts,  this 
power  is  not  great. 

Finely  divided  metals  are,  in  certain  cases,  able  to  absorb  consid- 
erable amounts  of  gases,  but  this  aptitude  is  always  specific  and 
limited  to  a  small  number  of  gases.  In  the  case  of  charcoal,  the 
amounts  of  various  gases  absorbed  are  roughly  in  proportion  to  their 


136  CATALYSIS  IN  ORGANIC  CHEMISTRY  40 

ease  of  liquefaction,  while  with  metals  the  absorption  is  markedly 
characterized  by  a  sort  of  selective  affinity. 

136.  It  is  one  of  the  most  difficultly  liquefiable  gases,  hydrogen, 
that  is  absorbed  the  most  readily  by  metallic  powders.   The  maximum 
of  such  absorption  is  shown  by  palladium,  which,  in  the  form  of 
sponge,  can  absorb  680  to  850  times  its  own  volume  of  hydrogen, 
whatever  be  the  pressure  of  the  gas,  provided  the  pressure  be  not  too 
low:    for  all  of  the  hydrogen  is  given  up  in  a  vacuum,  even  in  the 
cold.5 

At  20°,  platinum  black  absorbs  110  volumes  of  hydrogen,  what- 
ever the  pressure,  provided  it  is  more  than  200  mm.,  and  here,  like- 
wise, the  hydrogen  is  given  up  in  a  vacuum.6 

Reduced  cobalt  can  absorb  153  volumes  of  hydrogen,  finely  divided 
gold,  46,  reduced  iron  or  reduced  nickel,  up  to  19,  and  reduced  copper, 
only  4.7 

137.  The  precious  metals  have  an  analogous,  though  less  energetic 
affinity  for  oxygen.    Thus  platinum  black  absorbs  up  to  100  volumes 
of  oxygen  in  the  cold  and  here  again  this  amount  is  not  increased  by 
additional  pressure  and  all  of  the  gas  is  given  up  in  a  vacuum. 

Finely  divided  gold  and  silver  can  also  take  up  greater  or  less 
amounts  of  oxygen.8 

138.  The  activity  of  these  finely  divided  metals,  as  hydrogenation 
or  oxidation  catalysts,  would  then  be  due  to  their  power  to  absorb 
hydrogen  or  oxygen  along  with  the  vapor  which  is  to  be  transformed. 
The  compression  and  local  heating  thus  produced  would  cause  the 
reaction  to  take  place  which  without  this  help  would  have  required 
a  much  higher  temperature,  frequently  a  temperature  so  high  that 
the  products  would  not  be  stable. 

The  dehydrations  of  alcohols  which  are  effected  by  contact  with 
alumina,  would  result  from  the  condensation  of  the  alcohol  vapors  in 
the  pores  of  the  alumina,  this  condensation  producing  effects  compa- 
rable to  superheating  the  vapors. 

139.  The  powdered  or  porous  state  would  be  a  sufficient  condition 
to  produce  such  effects,  since  a  body  containing  an  infinite  number 
of  very  small  cavities,  offers  the  possibility  of  realizing  simultaneously 

6  MONO,  RAMSAY,  and  SHIELDS,  Phil  Trans.  Roy.  Soc.,   186,  657   (1896). 
Proc.  Roy.  Soc.,  62,  50  and  290  (1897).    DEWAR,  Chem.  News,  76,  274  (1897). 

6  MOND,  RAMSAY  and  SHIELDS,  Phil.  Trans.  Roy.  Soc.,  186,  675  (1896). 

7  MOISSAN,  Traite  de  Chimie  Mineral,  I,  13. 

8  NEUMANN,  Monatsh.,  13,  40  (1892).    MONO,  RAMSAY  and  SHIELDS,  Proc. 
Roy.  Soc.,  62,  50  (1897)  and  Zeit.  phys.  Chem.,  25,  657  (1898).    RAMSAY  and 
SHIELDS,  Phil.  Trans.  Roy.  Soc.,  186,  657  (1896).    ENGLER  and  WOCHLER,  Zeit. 
anorg.  Chem.,  29,  1   (1901). 


41  THE  MECHANISM  OF  CATALYSIS  142 

all  possible  temperatures  and  all  possible  pressures  thus  causing  a 
great  number  of  reactions  by  condensation  and  heating.9  To  this 
local  pressure,  there  is  added  also,  in  the  case  of  metals,  the  effect  of 
immediate  contact  with  a  good  conductor  and,  consequently,  electrical 
influences  which  might  aid.10 

140.  A  reaction  which,  without  the  aid  of  the  catalyst,  would  take 
place  at  an  infinitely  slow  rate,  at  the  temperature  of  the  experiment, 
would  thus  receive,  on  account  of  the  pressure  of  the  catalyst,  an 
immense  acceleration  and  go  to  completion  in  a  relatively  short  time. 

Catalysis  would  then  be,  as  Ostwald J1  has  defined  it,  only  the 
acceleration  of  a  chemical  phenomenon  which  otherwise  would  take 
place  slowly.  The  presence  of  the  catalyst  in  the  system  suppresses 
the  chemical  friction  which  slows  up  the  reaction  to  the  point  of  stop- 
ping it  entirely.  Its  role  would  then  be  similar  to  that  of  oil  in  clock- 
work, the  movement  of  which  it  accelerates,  though  the  forces  which 
produce  the  movement  are  not  increased. 

141.  This  physical  explanation,  applicable  to  all  porous  catalysts, 
meets  with  objections  numerous  and  difficult  to  get  rid  of. 

Right  at  the  start,  the  cause  which  determines  the  condensation 
of  gases  and  vapors  in  the  pores  of  a  solid  remains  mysterious  and 
inexplicable;  this  physical  attraction  of  solids  for  gaseous  substances 
presents  no  visible  relation  to  the  properties  of  the  gases.  The  absorp- 
tion by  wood  charcoal  is  indeed  greater  for  gases  which  are  readily 
liquefied,  but  it  is  just  the  other  way  with  platinum  and  various  metal 
powders  where  the  gas  that  is  most  absorbed  is  hydrogen  which  is 
very  difficult  to  liquefy. 

The  same  theory  is  difficult  to  apply  to  the  case  where  hydrogen 
is  taken  up  with  the  aid  of  platinum  black  or  nickel  held  in  suspen- 
sion in  a  liquid  medium  (Chapters  XI  and  XII) ,  and  even  more  dif- 
ficult where  the  catalyst  is  colloidal  platinum  or  palladium:  for  it  is 
difficult  to  see  how  high  local  pressures  and  temperatures  could  be 
developed  in  such  cases. 

142.  Furthermore,  a  purely  physical  conception  of  the  causes  of 
the  reaction  does  not  take  account  of  the  specificity  of  catalysts  and 
of  the  remarkable  diversity  of  the  effects  produced. 

At  the  same  temperature,  300°,  the  vapors  of  an  alcohol,  isobutyl, 
for  example,  decompose: 

in  the  presence  of  copper,  into  aldehyde  and  hydrogen,  exclusively ; 
in  the  presence  of  alumina ,  into  isobutylene  and  water,  exclusively; 

9  DUCLAUX,  Compt.  rend.,  152,  1176  (1911). 

10  VAN'T  HOFF,  Lemons  de  Chim.  Phys.,  1898,  3,  216. 

11  OSTWALD,  Rev.  Sci.,  1902  (1),  640. 


143  CATALYSIS  IN  ORGANIC  CHEMISTRY  42 

in  the  presence  of  uranium  oxide,  both  ways,  giving  at  the  same 
time  the  aldehyde  and  isobutylene. 

Manganous  oxide  gives  the  same  decomposition  as  copper,  only 
slowly. 

If  we  assume  that  the  metallic  characteristic  of  conductivity 
accounts  for  the  fundamental  difference  between  copper  and  alumina; 
we  can  not  explain  the  differences  between  alumina,  and  the  oxides 
of  manganese  and  uranium,  if  the  physical  condensation  in  the  pores 
of  the  catalyst  is  the  sole  cause  of  catalysis. 

The  action  of  the  catalytic  oxide  can  not  be  entirely  like  an  eleva- 
tion of  temperature,  since  the  direction  of  the  reaction  is  intimately 
connected,  not  with  the  physical  state  of  the  oxide,  but  with  its 
chemical  nature. 

143.  The  decomposition  of  formic  acid  furnishes  a  no  less  striking 
example  of  the  specificity  of  catalysts  (821).    Finely  divided  metals 
and  likewise  zinc  oxide,  decompose  this  acid  into  hydrogen  and  carbon 
dioxide  exclusively,  but  at  the  same  temperature,  titanium  oxide  gives 
carbon  monoxide   and   water   exclusively,   while   certain   oxides,   as 
thoria,  bring  about  a  mixed  reaction,  more  or  less  complicated  by  the 
production  of  formaldehyde  and  even  of  methyl  alcohol. 

Yet  from  the  physical  point  of  view  there  does  not  appear  to  be 
any  great  difference  between  the  oxides  of  zinc,  titanium,  and  thorium. 

144.  Furthermore,  this  explanation  of  catalysis  can  not  possibly 
apply  to  the  effects  of  liquid  catalysts  in  homogeneous  systems  and 
it  is  hard  to  imagine  that  there  are  fundamental  differences  between 
the  various  kinds  of  catalysis. 


CHEMICAL  THEORY  OF  CATALYSIS 

145.  An  entirely  general  explanation  of  catalytic  phenomena  can 
be  based  on  the  idea  of  the  temporary  formation  of  unstable  chemical 
compounds  which,   serving   as   intermediate   steps   in  the   reaction, 
determine  its  direction  or  increase  its  velocity. 

In  order  to  arrive  at  a  clearer  idea  of  the  catalytic  mechan- 
ism, a  special  case  can  be  first  considered  which  can  be  classed 
as  catalytic  and  which  can  be  designated  by  the  name  reciprocal 
catalysis. 

146.  Reciprocal     Catalysis.      Suppose    two     distinct     chemical 
systems  capable  of  reacting  independently,  each  on  its  own  account: 
however,  each  one  of  them,  if  left  to  itself,  remains  in  false  equilibrium 
or,  at  least,  reacts  with  extreme  slowness.    But  if  these  two  systems 


43  THE  MECHANISM  OF  CATALYSIS  148 

are  mixed,  they  mutually  catalyze  each  other  and  the  two  reactions 
proceed  simultaneously  very  rapidly  in  correlative  proportions.12 

147.  An  example  is  furnished  by  hydrogen  peroxide,  opposed  by 
chromic  acid,  H2Cr04.    The  hydrogen  peroxide  tends  to  decompose 
into  water  and  oxygen,  but  in  the  cold,  this  spontaneous  decomposi- 
tion is  very  slow  and  would  require  more  than  a  year. 

The  chromic  acid  solution,  acidified  with  sulphuric  acid,  is  also 
stable  in  the  cold,  but,  if  heated  it  decomposes  with  evolution  of 
oxygen.  On  heating,  we  would  have: 

3  H202  =  3H20  +  30 
and         2  H2Cr04  +  3  H2S04  =  Cr2(S04)3  +  5  H20  +  30. 

But  if  the  two  solutions  are  mixed  cold,  in  the  exact  proportions 
represented  by  the  formulae  above,  there  is  immediate  decomposition, 
simultaneous  and  complete,  of  both  the  hydrogen  peroxide  and  the 
chromic  acid,  and  this  decomposition,  manifested  by  a  brisk  effer- 
vescence of  oxygen,  takes  place  in  such  a  manner  that  the  amount  of 
oxygen  coming  from  the  hydrogen  peroxide  is  exactly  -the  same  as 
that  from  the  chromic  acid. 

This  proportionality  indicates  the  cause  of  the  reaction,  which  is 
apparently  the  production  of  an  unstable  combination  of  hydrogen 
peroxide  and  chromic  acid  in  the  proportion  3  H202  :  2  H2Cr04. 
As  soon  as  this  compound  is  formed,  it  decomposes,  with  liberation 
of  oxygen,  leaving  water  and  chromic  oxide  which  dissolves  in  the 
sulphuric  acid  present. 

This  fugitive  combination,  the  temporary  formation  of  which  de- 
stroys the  false  equilibrum  of  the  two  systems,  really  exists:  for  it 
appears  as  an  intense  blue  coloration,  when  the  two  liquids  are  mixed, 
and  can  even  be  isolated.  If  a  dilute  solution  of  hydrogen  peroxide 
is  poured  into  a  slight  excess  of  chromic  acid:  in  place  of  a  stormy 
effervescence  a  blue  solution  is  obtained.  When  this  is  shaken  with 
ether,  the  dark  blue  unstable  compound  passes  into  the  ether.  The 
evaporation  of  the  ether  at  — 20°,  leaves  a  dark  blue  oil,  which,  on 
warming  to  room  temperature,  decomposes  into  chromic  oxide,  water, 
and  oxygen.  We  have  in  succession,13 

2H2Cr04  +  3  H202  =  4  H20  +  H2Cr2O10 

H2Cr2O10  —  Cr203  +  H20  +  3  02. 

148.  Another  example  of  reciprocal  catalysis  is  offered  by  an  acid 
solution  of  potassium  permanganate  opposed  by  hydrogen  peroxide. 

12  SABATIER,  Rev.  gen.  de  Chimie  pure  et  app.,  17,  185  (1914). 

13  MOISSAN,  Traite  de  Chimie  Min.,  I,  275  (1904). 


149  CATALYSIS  IN  ORGANIC  CHEMISTRY  44 

The  permanganate  which  is  itself  an  energetic  oxidising  agent,  reduces 
the  hydrogen  peroxide  immediately,  and  is  itself  reduced.  Here  again 
there  is  exact  equality  between  the  amounts  of  oxygen  coming  from 
the  two  reacting  substances. 

A  solution  of  potassium  permanganate,  acidified  with  sulphuric 
acid,  is  stable  in  the  cold,  but  when  heated  there  is  a  slow  reaction: 

2  KMnO,  +  3  H2S04  =  2  MnS04  +  K2S04  +  3  H20  +  5  0. 

Likewise  the  hydrogen  peroxide  alone  would  give  very  slowly  in  the 
cold: 

5  H202  =  5  H20  +  5  0. 

On  mixing  the  two  solutions  there  is  immediately  a  vigorous  effer- 
vescence, liberating  10  0.  The  reaction  ia  quantitative  and  is  used 
practically  for  the  estimation  of  hydrogen  peroxide  by  titrating  with 
standard  potassium  permanganate  solution.  As  in  the  case  of 
chromic  acid,  this  proportionality  indicates  the  formation  of  an  un- 
stable compound,  the  decomposition  of  which  disengages  5  02;  but  in 
this  case  it  is  difficult  to  detect.  According  to  Berthelot,  the  perman- 
ganate acts  on  hydrogen  peroxide  to  substitute  hydroxyl  groups  for 
the  hydrogen  atoms,  furnishing  a  sort  of  hydrogen  tetroxiae: 

0— OH 
0— OH 

which  is  very  unstable  and  soon  decomposes  into  water  and  3  0. 
When  the  solutions  are  mixed  at  — 12°,  the  permanganate  is  de- 
colorized without  the  evolution  of  oxygen,  but  the  colorless  tetroxide, 
stable  at  — 12°,  decomposes  on  warming,  liberating  the  oxygen.  Po- 
tassium and  caesium  tetroxide,  which  are  known,  are  the  alkaline 
salts  of  this  hydrogen  tetroxide.14 

Thus  in  reciprocal  catalysis  the  simultaneous  and  correlated  re- 
actions of  two  systems,  which  apart  only  tend  to  react,  are  determined 
by  the  production  of  an  unstable  combination  which  serves  as  a 
common  intermediate  product  for  the  two  reactions.  This  inter- 
mediate compound  is  sometimes  visible  as  in  the  case  of  the  hydrogen 
peroxide-chromic  acid  and  sometimes  difficult  to  perceive  as  in  the 
case  of  the  hydrogen  peroxide-permanganate  mixture. 

149.  Induced  Catalysis.  Suppose  a  chemical  system  which  tends 
to  react  but  which  remains  in  false  equilibrum  or  undergoes  change 
infinitely  slowly.  But  if  another  system  which  is  reacting  rapidly 
in  an  analogous  manner  be  associated  with  the  first,  the  first  system 
is  drawn  into  the  reaction,  without  the  second  seeming  to  take  any 

"  BERTHELOT,  Ann.  CUm.  Phys.  (5),  21,  176  (1880)  and  (7),  22,  433  (1901). 


45  THE  MECHANISM  OF  CATALYSIS  151 

part  in  the  reaction  of  the  first,  except,  so  to  speak,  setting  it  an  ex- 
ample. This  may  be  called  induced  catalysis,  and,  as  in  the  case  of 
reciprocal  catalysis,  there  is  found  to  be  a  proportionality  between 
the  two  reactions. 

Frequent  examples  of  reactions  of  this  sort  are  found  among  oxida- 
tions by  oxygen  gas  and  are  called  auto-oxidations. 

150.  Auto-oxidations.    A   large  number  of   substances  directly 
oxidisable  by  oxygen,  or  by  air,  stimulate  by  their  own  oxidation 
that  of  substances  which,  without  this  circumstance,  would  not  be 
directly  oxidisable. 

Thus  palladium  hydride  when  allowed  to  oxidise  spontaneously 
in  water  solution,  causes  intense  oxidations;  indigo  is  decolorized  and 
potassium  iodide  is  oxidised  into  potassium  hydroxide  and  iodine; 
ammonia  goes  into  nitric  acid,  benzene  into  phenol,  and  toluene  into 
benzoic  acid.  Carbon  monoxide  is  oxidised  to  the  dioxide,  an  oxida- 
tion which  ozone  and  hydrogen  peroxide  are  incapable  of 
accomplishing.15 

Ethyl  alcohol,  exposed  to  the  simultaneous  action  of  sunlight  and 
air,  is  not  appreciably  changed,  but  in  the  presence  of  xylene,  which 
is  oxidised,  the  alcohol  goes  into  acetic  acid:  under  the  same  condi- 
tions, amyl  alcohol  gives  valeric  acid,  and  mannite  yields  mannose.16 

Oxidations  of  the  same  nature  accompany  the  spontaneous  oxida- 
tion of  phosphorus  in  moist  air,  of  turpentine,  of  aqueous  solutions  of 
pyrogallol,  of  alkaline  sulphites,  of  ferrous  hydroxide,  of  ammoniacal 
cuprous  salts,  of  benzaldehyde,  etc.  Such  substances  are  called  auto- 
oxidisers,  and  experiment  has  shown  that  in  every  case  they  render 
active,  that  is  to  say,  able  to  oxidise  substances  otherwise  not 
attacked,  exactly  the  same  amount  of  oxygen  as  they  use  up  in  their 
own  oxidation.17 

151.  The  cause  of  the  phenomenon  appears  to  be  that  the  auto- 
oxidiser  takes  up  oxygen  to  form  a  sort  of  peroxide  which  is  then 
destroyed  in  the  oxidation  of  the  associated  substance. 

The  auto-oxidiser,  A,  alone  would  give: 

/° 

A  -f  0—Q  =  A(       - 

oxygen  \Q 

15  HOPPE-SEYLER,  Berichte,  12,  1551  (1879);  16,  1917  (1883);  20,  R795 
(1887);  BAUMANN,  Ibid.,  16,  2146  (1883);  17,  283  (1884).  REMSEN  and  REISER, 
Am.  Chem.  Jour.,  4,  154  (1883);  5,  424  (1884).  LEEDS,  Chem.  News,  48,  25 
(1883). 

18  CIAMICIAN  and  SILBER,  Berichte,  46,  3894  (1912). 

17  ENGLER  and  WILD,  Berichte,  30,  1669  (1897).  ENGLER,  Rev.  gen  de  Chim. 
pure  et  app.,  6,  288  (1903). 


152  CATALYSIS  IN  ORGANIC  CHEMISTRY  46 

Then  in  contact  with  the  oxidisable  substance,  B: 

X) 
A'  •  +  B  =  A:O  +  B:O. 

\0  stable  stable 

unstable 

/o 

The  temporary  formation  of  the  combination,  A      .  ,  is  the  deter- 


mining  cause  in  the  oxidation  of  the  substance  B,  which  would  not 
otherwise  have  taken  place. 

In  the  absence  of  B,  the  second  reaction  would  have  taken  place 
with  the  aid  of  a  second  molecule  of  A,  thus: 


A(  -  +  A  =  2(A:0). 
\0 

Whenever  this  latter  reaction  is  sufficiently  slow,  the  unstable 
peroxide  can  be  prepared,  by  the  action  of  oxygen  on  the  auto-oxidiser 
alone,  and  may  be  kept  for  a  time.  Thus  turpentine  shaken  with  a 
large  volume  of  air,  forms  a  peroxide  which,  later  on  in  the  absence 
of  air,  can  decolorize  indigo,  cause  guaiac  tincture  to  turn  blue,  or 
liberate  iodine  from  potassium  iodide. 

The  auto-oxidiser,  A,  is  not  a  catalyst,  since  it  oxidises  in  pro- 
portion to  its  own  mass,  and  since  it  does  not  emerge  unchanged  from 
the  reaction  which  it  has  caused. 

152.  Oxidation  Catalysts.  Let  us  suppose  that  in  the  case  of 
the  auto-oxidiser,  A,  opposed  by  the  oxidisable  substance,  B,  that  the 
latter  can  be  oxidised  not  only  at  the  expense  of  the  unstable 

/O 

peroxide,  A'    .  ,  but  also  by  reducing  the  stable  oxide,  A:0,  we  will 

\p 

then  have  the  succession  of  reactions: 


0 

7° 

A(  .  +  B  =  AO  +  BO 

\O 

AO  +  B  =  BO  +  A 

regenerated 

Thus  the  auto-oxidiser  would  be  entirely  regenerated  and  could 
again  serve  as  a  carrier  of  the  free  oxygen  to  the  oxidisable  substance. 
A  limited  amount  of  A  could  serve  to  oxidise  an  unlimited  amount  of 
B:  A  would  then  be  an  oxidation  catalyst. 


47  THE  MECHANISM  OF  CATALYSIS  154 

153.  This  condition  is  realized  by  cerium  salts  with  glucose  in 
alkaline  solution.  A  cerium  salt,  dissolved  in  the  presence  of  potas- 
sium carbonate,  is  a  colorless  auto-oxidiser.  We  have: 

Ce(OH)3  +  02  +  Ce(OH)3  =  Ce(OH)3 .0.0.  Ce(OH)3 


unstable   peroxide 

Water  reacts  with  this  compound: 

Ce(OH)3  .0.0.  Ce(OH)3  +  H20  = 

Ce(OH)4    +    Ce(OH)3.O.OH. 

eerie  hydroxide  blood  red 

The  blood-red  peroxide,  when  brought  into  contact  with  an 
oxidisable  substance,  such  as  potassium  arsenite,  oxidises  it,  returning 
to  the  state  of  the  stable  yellow  eerie  hydrate.  There  has  been  no 
catalysis.  But  if  glucose  is  added,  the  eerie  hydrate  oxidises  the 
glucose,  being  itself  reduced  to  cerous  hydroxide  which  can  re- 
commence the  cycle  of  reactions.  This  is  catalysis.18 

It  is  in  this  manner  that  small  amounts  of  manganous  salts  can 
cause  the  direct  oxidation  of  unlimited  quantities  of  pyrogallol  or 
hydroquinone.19 

154.  Platinum  and  Related  Metals.  The  activity  of  platinum 
and  related  metals  can  be  explained  by  a  similar  mechanism  (243). 
In  contact  with  oxygen,  a  sort  of  unstable  peroxide  is  produced  on 


the  surface   of  the  metal,   comparable   to   the   A     .    of   the   auto- 


oxidisers.  With  an  oxidisable  substance,  B,  there  is  production  of 
BO  and  AO,  but  the  unstable  AO  oxidises  another  molecule  of  B  to 
form  BO  and  free  A.  Under  these  conditions  the  platinum  would 
serve  to  render  the  oxygen  atomic,  and  since  the  platinum  is  regen- 
erated in  the  course  of  the  reaction,  the  cycle  can  be  repeated 
indefinitely. 

The  result  is  that  the  use  of  the  platinum  not  only  serves  to  lower 
the  otherwise  high  temperature  required  by  certain  oxidations  (e.  g. 
of  hydrogen  or  carbon  monoxide)  but  also  to  realize  other  oxidations 
which  can  not  be  accomplished  by  molecular  oxygen  at  any  tempera- 
ture whatsoever,  for  example,  the  liberation  of  iodine  from  potassium 
iodide,  which  is  effected  in  the  cold  by  aerated  20  platinum  black,  or 

18  JOB,  Ann.  Chim.  Phys.,   (7),  20,  207   (1900).    Compt.  rend.,   134,   1052 
(1902);  136,  45  (1903). 

19  BERTRAND,  Bull.  Soc.  Chim.,  (3),  17,  578  and  619  (1897).    VILLERS,  Ibid., 
(3),  17,  675  (1897). 

20  ENGLER  and  WOHLER,  Z.  anorg.  Chem.,  29,  1  (1901). 


155  CATALYSIS  IN  ORGANIC  CHEMISTRY  48 

the  production  of  nitric  acid  from  ammonia,  by  hot  platinum  sponge. 
These  fixations  and  liberations  of  oxygen  take  place  at  the  surface 
of  the  metal  and,  for  that  reason,  the  catalytic  power  is  proportional 
to  the  extent  of  that  surface:  it  is  immeasurably  greater  for  platinum 
sponge,  and  especially  for  the  black,  than  for  the  metal  in  foil  or 
wire. 

155.  General  Explanation  of   Catalysis.     The  idea  of  a  tem- 
porary unstable  combination  has  served  in  explaining  readily  the 
mechanism  of  reciprocal  catalyses  (146),  of  induced  catalyses  (150), 
and  also  of  catalyses  in  the  strict  sense  of  the  term,  such  as  direct 
oxidations  (152).    This  notion  can  be  generalized  and  applied  to  all 
sorts  of  catalyses. 

The  formation  and  decomposition  of  intermediate  compounds 
furnished  by  the  catalysts  usually  correspond  to  a  diminution  of  the 
free  energy  of  the  system  and  this  diminution  by  steps  is  frequently 
much  easier  than  the  immediate  direct  diminution,  somewhat  as  the 
use  of  a  staircase  facilitates  a  descent.  Ordinarily  these  successive 
step-downs  take  place  quite  rapidly,  though  rapidity  is  not  a  neces- 
sary condition  of  catalysis. 

These  intermediate  compounds  can  be  isolated  in  a  sufficiently 
large  number  of  cases  for  us  to  generalize  the  idea  and  assume  their 
formation  in  cases  in  which  we  can  not  prove  their  existence. 

156.  Catalyses  in  which  the  Intermediate  Compounds  can  be 
Isolated.    Berthelot  has  pointed  out  well  defined  examples  in  the 
decomposition  of  hydrogen  peroxide  by  alkalies  and  by  silver  oxide. 
We  will  cite  some  other  examples  belonging  to  very  different  types. 

Chlorination  of  Organic  Compounds.  In  order  to  facilitate  the 
direct  chlorination  of  a  liquid  organic  compound,  iodine  is  dissolved 
in  it.  The  chlorine  unites  with  it  to  form  iodine  trichloride,  IC13, 
which  could  be  isolated  if  the  iodine  were  alone,  but  which,  finding 
itself  in  contact  with  the  organic  substance,  gives  up  chlorine  to  it 
returning  to  the  lower  state  of  iodine  monochloride  which  the  free 
chlorine  transforms  into  the  trichloride,  this  process  being  repeated 
again  and  again,  thus: 

IC13  +  MH  =  HC1  +  MCI  +  IC1 
IC1  +  C12  —  IC1,. 

It  can  be  proved  that  the  chlorination  is  proportional  to  the  weight 
of  the  iodine  trichloride.  When  the  operation  is  carried  on  with  a 
continuous  current  of  chlorine,  the  trichloride  is  constantly  re- 
generated and  we  have  catalysis  (278). 

157.  The  mechanism  is  doubtless  the  same  for  all  of  the  anhydrous 


49  THE  MECHANISM  OF  CATALYSIS  169 

metal  chlorides  which  are  used  as  chlorine  carriers  in  direct  chlorina- 
tion  (283).  The  intermediate  products  are  easy  to  perceive  in  the 
case  of  the  chlorides  of  antimony,  thallium,  molybdenum,  etc.,  where 
several  different  degrees  of  chlorination  are  known  of  which  the 
highest  are  formed  by  direct  action  of  chlorine,  and  which  give  up 
chlorine  to  the  organic  substance,  returning  to  the  lower  stages  which 
again  take  up  chlorine. 

It  is  harder  to  see  in  the  case  of  aluminum  chloride,  for  which, 
by  analogy,  we  must  also  assume  a  higher  chloride,  possibly  due  to 
the  supplementary  valencies  of  the  chlorine  atoms.21 

158.  Manufacture    of    Sulphuric    Acid.     The    manufacture    of 
sulphuric  acid  in  the  lead  chamber  process  employs,  as  catalyst,  nitric 
oxide  which  intimately  mixed  with  the  reacting  gases   (sulphur  di- 
oxide, oxygen  of  the  air,  and  water  vapor)   serves  to  render  rapid 
the  reaction  which  would  otherwise  take  place  slowly.    The  produc- 
tion of  an  intermediate  product  is  doubted  by  no  one  although  there 
is  not  entire  agreement  as  to  the  true  nature  of  such  compound. 

159.  Action  of  Sulphuric  Acid  on  Alcohol.    The  mechanism 
of  the  action  of  concentrated  sulphuric  acid  on  alcohol  is  well  known 
and  is  designated  by  the  name  of  Williamson's  reaction.22    The  first 
reaction  is  the  production  of  ethyl  sulphuric  acid: 

CH3CH2OH  +  H2S04  =  H20  +  CH3CH2 . 0  .  S08H. 

The  latter,  at  140°,  reacts  with  a  second  molecule  of  alcohol  to 
form  ether,  regenerating  sulphuric  acid: 

CH3CH2 . 0  .  S03H  +  CH3CILOH  =  H2S04  +  (CH3CH2)20. 

The  sulphuric  acid  can  again  form  ethyl  sulphuric  acid  and  so  on 
indefinitely,  since  the  temperature  is  high  enough  to  cause  the  elimi- 
nation of  the  water  along  with  the  ether.  Theoretically  the  action 
should  continue  indefinitely:  it  is  a  well  defined  case  of  catalysis. 
But  a  portion  of  the  sulphuric  acid  is  reduced  to  sulphur  dioxide 
gradually  diminishing  the  amount  of  the  acid. 

If  the  mixture  is  heated  higher,  towards  160-170°,  the  ethyl  sul- 
phuric acid  is  rapidly  decomposed  into  sulphuric  acid  and  ethylene: 

CH3CH2 .  0  .  S03H  =  H2S04  +  CH2  :  CH2. 

The  regenerated  sulphuric  acid  can  repeat  the  reaction  on  the 
alcohol  and  hence  is  a  catalyst  for  the  formation  of  ethylene  from 

21  It  is  possible  to  consider  this  a  case  of  the  FRIBDBL  and  CRAFTS  reaction, 
the  aluminum  chloride  combining  with  the  hydrocarbon  to  form  an  intermediate 
complex  which  reacts  readily  with  C1-C1  as  it  does  with  C1R.  — E.  E.  R. 

22  WILLIAMSON,  /.  Chem.  Soc.,  4,  106,  229  and  350  (1852). 


160  CATALYSIS  IN  ORGANIC  CHEMISTRY  50 

unlimited  amounts  of  alcohol  and  can  continue  this  function  so  long 
as  it  is  not  too  much  diminished  by  reduction  to  sulphur  dioxide. 
This  reduction  is  more  serious  in  this  case  as  the  reaction  temperature 
is  higher. 

160.  Hydrogen   Peroxide.     In  the   catalytic   decomposition   of 
hydrogen  peroxide  by  alkalies  and  alkaline  earths,  unstable  inter- 
mediate compounds  are  plainly  formed  and  can  be  isolated.23 

The  intermediate  steps  are  equally  visible  in  many  catalyses 
brought  about  in  gaseous  and  liquid  media  by  solid  catalysts. 

161.  Squibb's  Method.    A  fine  example  is  the  method  of  Squibb 
for  the  preparation  of  acetone 24   (837) . 

If  acetic  acid  vapors  are  passed  over  calcium  carbonate  heated 
to  400°,  calcium  acetate  is  produced  with  the  liberation  of  carbon 
dioxide.  If  the  acid  is  discontinued  and  the  temperature  is  raised 
to  500°,  the  calcium  acetate  is  decomposed,  regenerating  the  car- 
bonate and  liberating  acetone: 

At  400°          2  CH3C02H  +  CaC03  =  C02  +  H20  +  (CH3C02)2Ca 
At  500°  (CH3C02)2Ca  =  CaCO3  +  CH3 .  CO  .  CH3. 

If  the  acetic  acid  is  passed  over  the  calcium  carbonate  at  500°, 
it  is  evident  that  the  first  reaction  will  tend  to  take  place  with  the 
formation  of  calcium  acetate,  but  this  would  decompose  immediately 
to  form  acetone:  the  calcium  carbonate  would  then  be  a  catalyst 
(839),  the  reaction  being: 

2  CH3C02H  =  C02  +  H20  +  CH3 .  CO  .  CH3. 

162.  Catalytic  Oxidation  by  Copper.     If  a  current  of  oxygen 
is  passed  over  copper  heated  to  250°,  a  layer  of  oxide  is  formed: 
if  the  vapors  of  an  organic  compound,  such  as  an  aliphatic  hydro- 
carbon, are  passed  over  the  copper  so  oxidised,  at  the  same  tempera- 
ture, they  are  immediately  oxidised  with  the  production  of  water, 
carbon  dioxide,  etc.,  and  with  regeneration  of  metallic  copper.    If 
the  hydrocarbon  vapors  and  the  oxygen  are  sent  together  over  the 
copper  at  the  same  temperature,  there  is  production  of  the  oxide  and 
immediate  reduction  of  the  oxide  by  the  hydrocarbon;  the  copper 
functions  as  a  catalyst.     The  total  heat  of  oxidation  may  be  great 
enough  to  carry  the  metal,  on  the  surface  of  which  it  is  taking  place, 
to  incandescence.25    It  is  easy  to  see  that  copper  oxide  is  the  inter- 
mediate step. 

23  SCHONE,  Annalen,  192,  257  (1878)  and  193,  241  (1878).  BERTHELOT,  Ann. 
Chim.  Phys.,  (5),  21,  153  (1880). 

2*  SQUIBB,  J.  Amer.  Chem.  Soc.,  17,  187  (1895)  and  18,  231  (1896).  CONROY, 
J.  Soc.  Chem.  Ind.,  21,  302  (1902).  Rev.  gen.  Sc.,  13,  563  (1902). 

25  SABATIER  and  MAILHE,  Compt.  rend.,  142,  1394  (1905). 


51  THE  MECHANISM  OF  CATALYSIS  166 

163.  Action  of  Nickel  on  Carbon  Monoxide.    Another  example 
of  the  same  kind  is  furnished  by  the  destruction  of  carbon  monoxide 
by  nickel  at  300°. 

Carbon  monoxide  acting  on  reduced  nickel  around  100°,  produces 
nickel  carbonyl,  Ni(CO)4.  This  warmed  to  about  150°  decomposes 
completely  into  carbon  monoxide  and  nickel,  while  from  250°  to  300°, 
it  decomposes  entirely  differently,  into  nickel,  carbon,  and  carbon 
dioxide: 

Ni(CO)4  =  Ni  +  2C  +  2C02. 

If  carbon  monoxide  is  passed  over  nickel  at  150°,  there  appears 
to  be  no  action  since  the  nickel  carbonyl  that  is  formed  is  decomposed 
immediately,  in  place,  into  carbon  monoxide  and  carbon.  If  the 
operation  is  carried  on  at  300°,  there  should  still  be  the  production 
of  nickel  carbonyl  but  it  is  at  once  decomposed  into  carbon  dioxide, 
carbon,  and  nickel.  The  regenerated  nickel  can  carry  on  the  trans- 
formation of  carbon  monoxide  into  carbon  and  carbon  dioxide 
indefinitely. 

164.  Catalyses  in  which  the  Intermediate  Compounds  can  not 
be  Isolated.     In  the  cases  given  above,  the  intermediate  products 
which  serve  as  stepping-stones  for  the  reaction  can  be  readily  ob- 
served and  even  isolated  as  well  defined  chemical  compounds,  but  in 
more  numerous  cases,  these  intermediate  steps  are  difficult  to  per- 
ceive and  it  is  only  by  analogies  that  we  can  surmise  their  nature 
with  more  or  less  uncertainty. 

165.  Hydrogenation  by  Finely  Divided  Metals.     The  catalytic 
role  of  finely  divided  metals,  nickel,  copper,  platinum,  etc.,  in  direct 
hydrogenation  is  easily  explained  by  the  assumption  of  unstable  hy- 
drides on  their  surfaces.26    Such  condensation  of  hydrogen  actually 
takes  place  to  a  certain  extent,  as  we  have  seen  above   (136),  and 
particularly   with   palladium,    a   really    definite    combination   takes 
place  in  the  cold.    This  has  only  a  feeble  dissociation  pressure  and 
has  been  assigned  the  formula,  Pd3H2,  by  Dewar.27 

26  According  to   WILLSTATTER   and   WALDSCHMIDT-LEITZ    (Berichte,   54,    120 
(1921)  )  oxygen  must  be  present  for  hydrogenation  to  take  place.    They  assume 
that  the  platinum  combines  with  the  oxygen  first  to  form  a  sort  of  peroxide 
which  then  unites  with  the  hydrogen: 

/O  /O  H\     /O 

pt  +  02  ->  Pt     •  and  Pt      •  +  H2  ^       Pi      • 

\0  \0  H/     \0 

This  peroxide  hydride  is  the  active  intermediate  compound,  passing  its  hydrogen 
on  to  the  substance  to  be  hydrogenated  and  taking  up  more.  —  E.  E.  R. 

27  DEWAR,  Chem.  News,  76,  274  (1897). 


166  CATALYSIS  IN  ORGANIC  CHEMISTRY  52 

The  hydrogen  thus  combined  with  palladium  is  able  to  produce 
many  reactions  which  free  hydrogen  can  not.  It  combines  directly 
in  the  cold  and  in  the  dark  with  chlorine  and  with  iodine  as  well  as 
with  oxygen.28  It  reduces  chlorates  to  chlorides,  nitrates  to  nitrites, 
ferric  salts  to  ferrous,  mercuric  to  mercurous,  potassium  ferricyanide 
to  ferrocyanide,  indigo  blue  to  indigo  white,  sulphur  dioxide  to  hydro- 
gen sulphide,  and  arsenic  trioxide  to  arsenic.29  It  transforms  benzoyl 
chloride  into  benzaldehyde  and  nitrobenzene  into  aniline.30 

166.  Hydrogen  occluded  by  platinum  produces  analogous  effects.31 
Thus  when  the  vapors  of  nitrobenzene  are  directed  onto  platinum 
black  previously  charged  with  hydrogen,  all  the  hydrogen  which  is 
present  is  utilized  in  the  production  of  aniline.     If  at  this  moment, 
more  hydrogen  is  introduced,  a  new  fixation  takes  place  followed  by 
a  further  reduction  of  nitrobenzene. 

If  the  hydrogen  and  nitrobenzene  vapors  arrive  simultaneously, 
there  will  be  continuous  reduction  of  the  latter;  the  platinum  is  a 
hydrogenation  catalyst. 

The  catalysis  appears  to  be  a  consequence  of  the  occlusion  of  the 
hydrogen,  that  is  to  say,  of  the  formation  of  a  sort  of  combination 
of  the  hydrogen  and  the  metal  and  the  use  of  platinum  as  a  catalyst 
is  advantageous  since  the  interchange  of  gases  is  rapid  with  it. 

Palladium,  although  it  absorbs  much  more  hydrogen,  is  usually 
inferior  to  platinum,  probably  because  the  hydrogen  is  not  given  up 
rapidly  enough  to  the  molecules  to  be  hydrogenated. 

167.  Copper,  iron,  cobalt,  and  especially   nickel,   reduced   from 
their  oxides  are  still  more  advantageous,  although  they  can  retain 
only  small  amounts  of  free  hydrogen,  probably  because  the  forma- 
tion and  decomposition  of  the  hydrogen  addition  products  are  much 
more  rapid. 

With  nickel,  the  process  goes  on  as  if  there  were  formed,  on  the 
surface,  an  actual  unstable  hydride  capable  of  liberating  hydrogen 
in  the  atomic  condition  and  consequently  more  active  than  the  original 
molecular  hydrogen.  The  facts  lead  even  to  the  idea  that  there  are 

two  stages  in  the  fixation  of  hydrogen  such  as    • !          and  Ni(  „; 

Ni — 11  \H 

the  latter  more  active  combination  being  formed  by  metal  reduced 
from  the  oxide  below  300°  and  capable  of  more  kinds  of  work.  The 
former,  less  active  combination,  would  be  produced  by  nickel  reduced 
above  700°,  or  made  from  the  chloride  and  able  to  hydrogenate  ethy- 

28  BOETTGER,  Berichte,  6,  1396  (1873). 

29  GLADSTONE  and  TRIBE,  Chem.  News,  37,  68  (1878). 

80  KOLBE  and  SAYTZEFP,  J.  prakt.  Chem.,  (2),  4,  418  (1871). 

81  GLADSTONE  and  TRIBE,  loc.  cit.    COOKE,  Chem.  News,  58,  103  (1888). 


53  THE  MECHANISM  OF  CATALYSIS  170 

lenic  compounds,  nitriles,  and  nitro  bodies  but  not  the  aromatic 
nucleus. 

The  catalytic  hydrogenation  of  an  ethylene  hydrocarbon  would 
be  represented  by: 

H2  +  Ni2  —  Ni2H2. 
Ni2H2  +  C2H4  =  C2H6  +  Ni2. 

The  regenerated  nickel  would  continue  indefinitely  to  produce 
this  effect  so  long  as  the  hydrogen  and  ethylene  continued  to  arrive 
simultaneously. 

168.  If  finely  divided  metals  with  free  hydrogen  give  quickly 
formed  and  readily  decomposable  unstable  hydrides,  they  should  also 
be  able  to  take  hydrogen  from  substances  which  hold  it  only  feebly 
and  should  be  dehydrogenation  catalysts.    In   general,   experiment 
has  verified  this  prediction  (651). 

169.  Dehydration  by  Anhydrous  Oxides.    The  dehydration  of 
alcohols  by  certain  oxides,  as  alumina,  thoria,  etc.,  can  be  interpreted 
readily  by  a  close  analogy  to  Williamson's  reaction. 

These  oxides  can  be  regarded  as  the  anhydrides  of  metallic  hy- 
droxides capable  of  exercising  the  acid  function,  whether  exclusively 
acid  as  with  silicic  or  titanic  acid,  or  either  acid  or  basic  (hydroxides 
of  aluminum,  thorium,  chromium,  etc.).  Thus  with  alumina,  the 
alcohol  vapor  would  give  an  unstable  aluminate  which  in  contact  with 
alcohol  would  decompose  to  give  ether,  or  at  a  higher  temperature 
would  immediately  decompose  evolving  ethylene;  the  regenerated 
alumina  would  be  able  to  carry  on  this  reaction  indefinitely: 

A1203  +  2C«H2n+1.OH  =  H20  +  Al202(OCnH2n+1)2 
Then      2CnH2n+i.OH  +  Al202(OCnH2n+i)2  =  2(CnH2n+1)2O  +  A12O2(OH)2 

ether 

and        A1202(OH)2  =  H2O  +  A1208 

or          AI202(OCnH2n+1)2  •  2CnH2n  +  A1202(OH)2 

hydrocarbon 

which  would  be  immediately  followed  by  the  dehydration  of  the 
alumina. 

Such  alcoholates  can  be  isolated  in  various  ways,  for  example, 
aluminum  ethylate,  which  is  decomposed  cleanly  into  ethylene  and 
alumina.32 

In  the  case  of  methyl  alcohol,  only  the  first  sort  of  reaction  is  pos- 
sible, but  in  most  other  cases  the  other  takes  place  exclusively.88 

170.  It  would  be  the  same  way  with  thoria  which  would  furnish 
with  alcohol  vapors,  a  sort  of  thorium  alcoholate  which  the  heat  de- 

32  GLADSTONE  and  TRIBE,  Jour.  Chem.  Soc.,  41,  5  (1882). 

88  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.,  (8),  ao,  349  (1910). 


171  CATALYSIS  IN  ORGANIC  CHEMISTRY  54 

composes  into  an  ethylene  hydrocarbon  and  thoria,  which  is  capable 
of  reproducing  the  same  effect  indefinitely.  If  this  is  the  case,  this 
sort  of  ester  would  be  capable  of  reacting  chemically  with  various 
substances  with  which  it  is  brought  into  contact  and  experiments 
have  bountifully  confirmed  the  predictions  made  by  Sabatier  and 
Mailhe  on  this  point.34 

In  contact  with  thoria,  alcohol  vapors  react  directly  with  hydro- 
gen sulphide  to  give  mercaptans  (743),  with  ammonia  to  form  amines 
(732),  with  phenols  to  produce  mixed  ethers  (789),  and  with  aliphatic 
acids  to  yield  esters  (762). 

171.  Decomposition  of  Acids.    In  the  decomposition  of  aliphatic 
acids  by  anhydrous  oxides  it  is  frequently  easy  to  perceive  the  inter- 
mediate compound  which  serves  as  a  stepping  stone  in  the  reaction; 
namely,  the  salt  formed  by  the  acid  and  the  oxide.    It  appears  un- 
decomposed  at  temperatures  lower  than  those  used  in  the  catalysis, 
as  is  the  case  with  lime  and  zinc  oxide  (841).    At  a  higher  tempera- 
ture the  salt  is  immediately  decomposed  to  form  the  ketone. 

This  intermediate  formation  ceases  to  be  apparent  when  the  acid 
is  passed  over  the  oxide  at  a  higher  temperature,  because  the  forma- 
tion of  the  salt  is  then  balanced  by  its  rapid  destruction.  For  certain 
oxides,  as  thoria  and  titania,  it  can  not  even  be  perceived  since, 
doubtless,  the  formation  does  not  take  place  at  a  lower  temperature 
than  the  decomposition,  but  the  analogy  is  so  close  that  we  can  not 
fail  to  assume  similar  mechanisms  with  all  of  the  oxides. 

172.  In  the  decomposition  of  formic  acid  by  metals  or  oxides 
(821),  the  intermediate  compounds  would  be  formed  either  from  the 
hydrogen    (passing  over  the  metals),   or  from  the   carbon   dioxide 
(fixed  by  the  zinc  oxide),  or  from  the  formic  acid  itself  giving  with 
the  oxide  a  formate  the  decomposition  of  which  would  vary  according 
to  its  nature.    The  molecule  of  this  acid  is  a  structure  with  little 
stability,  tending  to  decompose  in  the  two  directions,  into  CO  +  H20 
or  into  C02  +  H2  ;  the  affinity  of  the  catalyst  giving  a  transient  com- 
pound, decides  the  direction. 

173.  The  Friedel  and  Crafts  Reaction.     The  catalytic  activity 
of  anhydrous  aluminum  chloride  in  the  Friedel  and  Crafts  reaction 
(884)  can  be  explained  by  the  production  of  a  temporary  combination 
between  the  chloride  and  the  organic  material.    Thus  with  aromatic 
hydrocarbons,  we  would  have: 


C6R5H  +  A1C1,  =  HC1  +  AT 

\C0R5 

34  SABATIER  and  MAILHE,  Corn-pi,  rend.,  150,  823  (1910). 


55  THE  MECHANISM  OF  CATALYSIS  175 

The  latter  compound  would  react  immediately  on  the  halogen 
derivative  present  and  we  would  have: 

^Cl, 

Al  f          +  R'Cl  =  A1C13  +  R'.C«,R5. 

C6R5  regenerated 

The  regenerated  aluminum  chloride  would  react  again  with  the 
hydrocarbon  and  the  same  reactions  would  be  repeated.  It  is  then 
a  catalyst  and  a  small  amount  of  the  salt  should  effect  the  trans- 
formation of  an  unlimited  amount  of  the  mixture.  This  is  in  fact 
what  takes  place  in  some  cases  where  the  aluminum  chloride  can  con- 
dense a  hundred  tunes  its  own  weight  of  benzene  with  other  molecules. 

174.  Practically,  it  is  often  necessary  to  employ  large  amounts 
of  the  aluminum  chloride,  sometimes  even  several  times  the  weight 
of  the  aromatic  hydrocarbon.  For  this  reason  some  chemists  have 
questioned  the  catalytic  role  of  the  chloride.  It  is,  however,  not  to 
be  doubted,  as  the  necessity  of  sometimes  using  such  large  amounts 
of  the  catalyst  is  due  either  to  the  tardiness  of  the  reaction  in  some 
cases  and  the  desire  to  hasten  it  by  providing  for  the  formation  of  a 
large  amount  of  the  required  intermediate  compound  or,  in  other 
cases,  to  the  fact  that  the  aluminum  chloride  forms  stable  combina- 
tions with  some  of  the  reactants  which  withdraw  a  portion  of  it  from 
the  reaction.  The  reality  of  the  formation  of  addition  products  of 
the  aluminum  chloride  with  the  organic  compounds  has  been  estab- 
lished by  Gustavson  who  has  been  able  to  isolate  an  addition  product 
with  benzene,  an  orange  colored  oil,  A1C13.3C6H6,  decomposable  by 
water,35  and  in  the  case  of  the  mixture  of  benzene  and  ethyl  chloride, 
A1C13.(C2H4)2.3C6H6,  which  heat  dissociates  into  benzene  and 


,  which  is  stable  and  serves  as  catalyst  for  the  trans- 
(C,H4C1)2 
formation  of  the  mixture.36 

175.  Action  of  Acids  and  Bases  in  Hydrolysis.  In  the  de- 
compositions by  addition  of  water,  or  hydrolyses,  such  as  the  saponi- 
fication  of  esters  by  strong  mineral  acids  (313),  or  by  strong  bases 
(318),  the  inversion  of  cane  sugar,  the  decomposition  of  glucosides 
(327) ,  or  of  acetals  and,  inversely,  in  the  production  of  esters  in  pres- 
ence of  small  amounts  of  mineral  acids  (749),  the  active  factors  of 
the  catalysis  appear  to  be  the  ions  resulting  from  the  electrolytic  dis- 
sociation of  the  acid  or  base-37  The  activity  of  the  catalyst  is  closely 

35  GUSTAVSON,  Berichte,  n,  2151  (1878). 

36  GUSTAVSON,  Compt.  rend.,  136,  1065  (1903);  140,  940  (1905). 

37  VAN'T  HOFF,  Lemons  Chim.  Phys.,  1898,  III,  140. 


176  CATALYSIS  IN  ORGANIC  CHEMISTRY  56 

connected  with  the  amount  of  this  dissociation  and  the  velocity  is 
proportional  to  the  number  of  free  ions  in  the  solution. 

176.  In  saponifications  catalyzed  by  soluble;  bases,  the  active 
factors  are  the  hydroxyl  ions  resulting  from  the  electrolytic  dissocia- 
tion of  the  base  and  we  are  justified  in  believing  that  the  attack  on 
the  molecule  of  ester,  ROA,  derived  from  the  oxy-acid  AOH,  is  the 
work  of  the  OH  ions  derived  from  the  base.  Thus  with  caustic 
potash  we  would  have: 


( 
ROA  +     +    -ROH+     + 

litiF       [  K  J       Ifoohof      [K 


The  ionized  salt,  AOK,  is  formed  in  the  solution,  but  as  the  corre- 
sponding organic  acid,  AOH,  is  only  slightly  dissociated  into  ions, 
water  hydrolyzes  the  salt  to  give: 


The  acid,  AOH,  is  thus  liberated  and  the  ions  of  the  original  caus- 
tic potash  are  free  to  recommence  their  catalytic  action. 

In  the  saponification  of  esters  by  acids  it  is  the  hydrogen  ions  that 
cause  the  effect.  Thus  with  hydrochloric  acid,  we  have: 


(HI  (A) 

ROA+I  -  }  =  ROH  +  \  -  \ 

^       (Clj       Stoohoi       (Clj 


But  there  is  immediate  reaction  with  water  to  give: 

+  + 

fAl  (H) 

i-[+H20  =  AOH  +    -}- 

(Clj  mss      (cij 

The  regenerated  ions  of  the  initial  molecule  of  hydrochloric  acid 
can  repeat  the  reaction  and  so  indefinitely.  Esterification  is  brought 
about  according  to  the  same  mechanism  but  in  the  inverse  direction. 

178.  The  velocity  of  a  hydrolysis  of  this  sort  is  proportional  to 
the  number  of  ions  that  are  active  in  producing  it.  With  the  strong 
acids  at  such  dilutions  that  they  may  be  regarded  as  completely  dis- 
sociated, the  effect  will  be  independent  of  the  nature  of  the  acid  and 
proportional  to  the  concentration  only.  This  has  been  verified  for 
hydrochloric,  hydrobromic,  hydriodic,  nitric  and  chloric  acids.38  It 

s*  OSTWALD,  J.  prakt.  Chem.,  (2),  28,  449  (1883). 


57  THE  MECHANISM  OF  CATALYSIS  180 

is  the   same   way   with    strong   soluble   bases,    potassium,    sodium, 
barium,  and  calcium  hydroxides  in  sufficiently  dilute  solutions.39 

179.  Catalysis   in   general   appears   to   be  the   result  of   purely 
chemical  phenomena  accomplished  by  the  aid  of  the  catalyst  which 
gives,  with  one  of  the  elements  of  the  primitive  system,  a  temporary 
unstable  combination,  the  decomposition  of  which,  or  the  reaction  of 
which,  with  one  of  the  other  reactants,  determines  the  transformation 
of  the  system,  the  catalyst  being  regenerated  in  its  original  condition 
and  able  to  repeat  the  reaction  indefinitely. 

180.  Ostwald  has  criticised  the  conception  of  the  formation  of 
intermediate  compounds  because  it  does  not  rest  on  a  sufficiently 
exact  knowledge  of  the  reactions  and  because  it  would  be  further 
necessary  to  prove  that  the  succession  of  reactions  assumed  requires 
less  time  than  the  direct  reaction,  and  adds  that  no  theory  is  of 
value  in  the  absence  of  exact  measurements. 

To  tell  the  truth,  we  do  not  know  much  more  as  to  the  true  nature 
of  the  absorption  of  gases  and  vapors  by  porous  catalysts  or  even 
by  wood  charcoal;  this  absorption,  or  occlusion,  which  is  determined 
by  a  sort  of  selective  affinity  between  the  gas  and  the  solid  is  a  real 
solution  penetrating  to  a  certain  depth  in  the  solid  and  similar  to 
the  temporary  combination  which  we  have  assumed,  the  differentia- 
tion of  chemical  and  physical  phenomena  being  always  uncertain. 

The  theory  of  catalysis  by  means  of  intermediate  compounds  still 
contains  many  obscurities  and  has  the  fault  of  leaning  frequently 
on  the  assumption  of  hypothetical  intermediate  products  which  we 
have  not  yet  been  able  to  isolate,  but  it  is  the  only  hypothesis  that 
is  able  to  explain  catalysis  in  homogeneous  solution  and  has  the  merit 
of  applying  to  all  cases. 

As  far  aS  I  am  concerned,  this  idea  of  temporary  unstable  inter- 
mediate compounds  has  been  the  beacon  light  that  has  guided  all  my 
work  on  catalysis;  its  light  may,  perhaps,  be  dimmed  by  the  glare  of 
lights,  as  yet  unsuspected,  which  will  arise  in  the  better  explored 
field  of  chemical  knowledge.40  Actually,  such  as  it  is,  in  spite  of  its 
imperfections  and  gaps,  the  theory  appears  to  us  good  because  it  is 
fertile  and  permits,  in  a  useful  way,  to  foresee  reactions. 

39  REICHER,  Annalen,  228,  275  (1885).    OSTWALD,  J.  prakt.  Chem.,  (2),  35, 
112   (1887).    ARRHENIUS,  Zeit.  phys.  Chem.,  i,   110   (1887).    BUGARSZKY,  Ibid., 
8,  418  (1891)., 

40  SABATIER,  Berichte,  44,  2001  (1911). 


180a  CATALYSIS  IN  ORGANIC  CHEMISTRY  58 

THEORIES    OF    CONTACT    CATALYSIS 
By  WILDER  D.  BANCROFT 

180a.  For  purposes  of  discussion  the  theories  of  contact  catalysis 
may  be  grouped  under  three  headings:— 

1.  Stoichiometric  theory. 

2.  Adsorption  theory. 

3.  Radiation  theory. 

The  Stoichiometric  theory  is  the  one  most  commonly  held  because 
it  involves  nothing  new  or  strange.  According  to  this  theory,  one  or 
more  of  the  reacting  substances  forms  with  the  catalytic  agent  a 
definite  compound  which  then  reacts  in  such  a  way  as  to  give  the 
final  products.  In  the  catalysis  of  hydrogen  peroxide  by  mercury, 
the  intermediate  formation  of  mercuric  peroxide 41  can  be  detected 
by  the  eye,  because  there  is  an  intermittent  building-up  of  a  film 
which  then  breaks  down,  only  to  grow  again.  The  formation  of 
graphite  is  usually  preceded  by  the  formation  of  a  carbide.  The 
conversion  of  acetic  acid  into  acetone42  by  passing  the  vapor  over 
heated  barium  carbonate  presumably  involves  the  intermediate  for- 
mation of  barium  acetate.  In  the  catalytic  oxidation  of  carbon 
monoxide  it  is  usually  believed  that  there  is  an  alternate  oxidation 
and  reduction  of  the  oxides  which  act  as  catalytic  agents.  Hydrogen 
peroxide  is  said  to  oxidize  cobaltic  oxide  to  peroxide  and  to  be  de- 
composed catalytically  by  cobaltic  oxide.43  Nickel  peroxide  reacts 
quantitatively  with  hydrogen  peroxide;  but  the  resulting  oxide  is  not 
converted  back  into  peroxide  by  hydrogen  peroxide  and  consequently 
does  not  decompose  it  catalytically. 

180b.  While  there  are  undoubtedly  many  cases  of  contact  catalysis 
which  come  under  this  general  head,  it  does  not  follow  that  this  is 
the  only  type.  It  seems  improbable  that  it  would  be  so  difficult  to 
make  carbon  tetrachloride  if  the  chlorine,  which  is  absorbed  by  car- 
bon and  thereby  made  active,44  were  present  as  a  definite  compound 
of  carbon  and  chlorine.  Oxygen  absorbed  by  charcoal  will  oxidize 
ethyl  alcohol  to  acetic  acid 45  and  ethylene  to  carbon  dioxide  and 
water,  reactions  which  certainly  are  not  characteristic  of  any  known 

41  BREDIG  and  VON   ANTROPOFF,  Zeit.  Elektrochemie,   12,   585    (1906);    VON 
ANTROPOFF,  Jour,  prakt.  Chem.,  (2),  77,  273  (1908). 

42  SQUIBB,  Jour.  Am.  Chem.  Soc.,  17,  187  (1895). 

43  BAYLEY,  Phil.  Mag.,  (5),  7,  126  (1879). 

44  DAMOISEAU,  Compt.  rend.,  73,  60  (1876). 
48  CALVERT,  Jour.  Chem.  Soc.,  20,  293  (1867). 


59  THE  MECHANISM  OF  CATALYSIS  180d 

- 

oxide  of  carbon.  It  is  very  important  that  we  should  decide  in  each 
particular  case  whether  a  definite  intermediate  compound  is  formed 
and,  if  so,  what  compound.  Only  in  this  way  can  we  escape  from  the 
haziness  which  handicaps  so  much  of  the  work  on  catalysis.  For 
instance,  it  seems  obvious  to  account  for  the  hydrogenating  power 
of  pulverulent  nickel  by  postulating  the  formation  of  an  unstable 
hydride ;  but  the  recent  work  of  Professor  Taylor  of  Princeton  shows 
that  no  hydride  is  formed.  It  is  easy  to  account  for  the  different 
action  of  nickel,  thoria,  and  titania  on  ethyl  acetate  by  postulating 
the  formation  of  intermediate  compounds;  but  there  is  no  experi- 
mental evidence  that  these  hypothetical  compounds  would  break 
down  in  the  desired  way  if  formed.  To  this  day  people  are  not  agreed 
as  to  what  intermediate  compound  is  formed  in  the  Deacon  chlorine 
process. 

180c.  The  absorption  theory  does  not  postulate  the  intermediate 
formation  of  definite  chemical  compounds.  The  assumption  is  that 
the  absorption  of  the  substances  to  be  catalyzed  makes  them  more 
active  chemically.  This  may  occur  in  different  ways.  Since  the 
reaction  velocity  is  a  function  of  the  concentration,  it  was  natural 
to  ascribe  the  catalysis  of  oxyhydrogen  gas  by  platinum  to  the  in- 
creased concentration  at  the  surface  of  the  metal.  This  seems  to 
have  been  disproved  by  the  recent  experiments  in  which  oxyhydrogen 
gas  is  reported  to  be  quite  stable  in  presence  of  an  alkaline  solution 
when  under  a  pressure  of  three  thousand  atmospheres.  This  explana- 
tion will  not  suffice  to  account  for  the  cases  in  which  the  same  sub- 
stance decomposes  in  one  way  in  presence  of  one  catalytic  agent  and 
in  another  way  in  presence  of  another.  On  the  other  hand,  the  in- 
crease in  concentration  must  have  an  effect  in  some  cases  and  it  seems 
probable  that  this  could  be  found  most  easily  if  one  studies  a  re- 
action which  takes  place  at  a  measurable  rate  in  the  absence  of  a 
catalytic  agent,  say  ester  formation,  and  if  one  takes  an  extremely 
non-specific  absorbent,  such  as  Patrick's  silica  gel. 

180d.  Langmuir46  considers  that  an  adsorbed  gas  is  held  chemi- 
cally by  the  unsaturated  valences  at  the  surface  of  the  solid,  thus 
forming  a  new  type  of  compound  which  I  have  called  indefinite 
compounds  because  they  are  not  of  the  ordinary  type  and  because 
no  definite  formulas  can  be  written  for  them.  In  the  case  of  the 
adsorption  of  argon  by  charcoal,  for  instance,  we  should  have  to 
write  CxAry  where  x  varies  with  the  mass  of  the  charcoal  and  y 
with  its  surface  as  well  as  with  the  pressure  and  temperature. 
Chemical  reactions  may  take  place  either  between  adjacent  atoms 

46  Jour.  Am.  Chem.  Soc.,  37,  1139  (1915);  38,  1145  (1916). 


180e  CATALYSIS  IN  ORGANIC  CHEMISTRY  60 

on  the  surface  or  when  gas  molecules  strike  molecules  or  atoms  on 
the  surface.  So  far  as  the  catalytic  part  is  concerned  this  is  much 
the  same  as  the  view  of  Debus.47  "  If  now  a  piece  of  platinum  is 
placed  in  peroxide  of  hydrogen,  the  molecules  of  the  latter  will  place 
themselves  in  such  a  position  on  the  surface  of  the  platinum  that  one 
oxygen  atom  of  the  peroxide  is  turned  towards  the  platinum  and  as 
near  to  it  as  possible.  The  peroxide  is  polarized.  But  this  has  the 
effect  also  of  bringing  the  oxygen  atoms  of  different  molecules  of 
peroxide  in  such  close  proximity  on  the  surface  of  the  metal  that 
they  can  combine  to  form  common  oxygen,  the  decomposition  of  the 
peroxide  into  water  and  oxygen  and  the  development  of  energy  being 
the  consequence.  The  action  of  the  platinum  places  the  molecules 
of  the  peroxide  in  the  position  oj  reaction  towards  each  other." 

180e.  Langmuir  has  contemplated  the  possibility  of  a  reaction 
between  two  adsorbed  molecules  and  between  one  adsorbed  and  one 
free  molecule.  The  second  case  is  one  in  which  a  more  effective  col- 
lision is  produced.  This  is  a  perfectly  legitimate  hypothesis. 
According  to  the  kinetic  theory  the  reaction  velocity  is  proportional 
to  the  number  of  collisions  between  possibly  reacting  molecules;  but 
it  does  not  follow  at  all  that  two  molecules  react  every  tune 
they  collide.  If  a  large  number  of  collisions  is  necessary  on  an  aver- 
age before  a  pair  of  molecules  react,  anything  which  would  make 
these  collisions  more  helpful  might  increase  the  reaction  velocity 
enormously.  The  first  question  is  then  whether  there  is  any  evidence 
of  ineffective  collisions.  This  matter  has  been  studied  by  Strutt48 
who  comes  to  the  conclusion  that  a  molecule  of  ozone  reacts  every 
time  it  strikes  a  molecule  of  silver  oxide;  but  that  a  molecule  of  ac- 
tive nitrogen  collides  with  a  molecule  of  copper  oxide  five  hundred 
times  on  an  average  before  they  react,  while  two  molecules  of  ozone 
at  100°  collide  on  an  average  6  x  1011  times  before  they  react.  With- 
out insisting  on  the  absolute  accuracy  of  these  figures  there  is  evi- 
dently plenty  of  margin  for  an  increase  in  reaction  velocity  with 
ozone  at  100°  if  one  could  produce  more  effective  collisions.  Lang- 
muir 49  finds  that,  at  a  pressure  of  not  over  5  bars,  and  at  2770°  K, 
15%  of  all  oxygen  molecules  striking  a  tungsten  filament  react  with 
it  to  form  tungstic  oxide,  W03.  This  coefficient  increases  at  higher 
temperatures  and  at  3300°  K  about  50%  of  all  the  oxygen  molecules 
which  strike  the  filament  react  with  it  to  form  tungstic  oxide. 

4T  Jour.  Chem.  Soc.,  53,  327  (1888) ;  Cf.  HUFNER,  Jour,  prakt.  chem.,  (2), 
10,  385  (1874). 

«  Proc.  Roy.  Soc.,  87,  A,  302  (1912). 

49  Jour.  Am.  Chem.  Soc.,  35,  105  (1913);  38,  2270  (1916). 


61  THE  MECHANISM  OF  CATALYSIS  I80g 

180f.  It  is  possible  that  a  catalytic  agent  may  cause  one  molecule 
to  strike  another  amidships  instead  of  head-on  and  may  thereby 
increase  the  effectiveness  of  the  collisions.  It  is  not  impossible  that 
part,  at  least,  of  the  effect  of  solvents  on  reaction  velocity  may  be 
due  to  some  such  thing  as  this.  If  we  adopt  the  views  of  Debus  and 
Langmuir  on  oriented  adsorption,  all  sorts  of  things  become  possible. 
If  ethyl  acetate,  for  instance,  attaches  itself  to  one  adsorbent  by  the 
methyl  group,  to  another  by  the  ethyl  group,  and  to  a  third  by  the 
carboxyl  group,  it  might  very  well  be  that  bombardment  of  the  cap- 
tive molecule  by  free  ones  might  lead  to  very  different  reaction 
products  in  the  three  cases.  Such  a  suggestion  is  of  very  little  value, 
however,  unless  it  can  be  made  definite.  We  do  not  know  as  yet 
whether  ethyl  acetate  is  actually  adsorbed  in  one  way  by  nickel,  in 
another  way  by  thoria,  and  in  a  third  way  by  titania,  nor  do  we 
know  whether  the  difference  in  the  manner  of  adsorption,  assuming 
it  to  occur,  is  of  such  a  nature  as  to  account  for  the  differences  in 
the  reaction  products. 

180g.  It  is  possible  not  to  make  an  assumption  as  to  the  precise 
way  in  which  adsorption  takes  place  and  merely  to  consider  the  sur- 
face of  the  solid  as  acting  like  a  solvent.  If  the  chemical  potential 
of  a  possible  reaction  product  is  lowered  in  any  way,  there  is  an  in- 
creased tendency  for  that  reaction  product  to  form.50  If  one  treats 
a  substance  with  a  dehydrating  agent,  the  tendency  to  split  off  water 
is  increased.  If  a  substance  like  alcohol  can  react  in  two  different 
ways,  we  should  expect  a  given  catalytic  agent  to  accelerate  the  re- 
action producing  the  reaction  products  which  are  adsorbed  the  most 
strongly  by  that  catalytic  agent.51  This  appears  to  happen  in  the 
simpler  cases.  Ipatief 52  states  that  the  decomposition  of  alcohol 
into  ethylene  and  water  in  presence  of  heated  alumina  is  due  to  the 
taking  up  of  water  by  the  alumina.  That  alumina  takes  up  water 
very  strongly  was  shown  by  Johnson,53  who  found  that  up  to  a  cer- 
tain point  alumina  adsorbs  water  vapor  as  completely  as  does  phos- 
phorus pentoxide.  Sabatier  attributed  the  decomposition  of  alcohol 
into  acetaldehyde  and  hydrogen  in  presence  of  pulverulent  nickel  to 
the  tendency  to  formation  of  a  nickel  hydride.  Both  he  and  Ipatief 
assume  the  formation  of  definite  compounds;  but  the  argument  is 
just  as  strong  in  case  we  postulate  that  the  catalytic  agent  adsorbs 
the  reaction  products  strongly  instead  of  combining  with  them.  An 

60  MILLER,  Jour.  Phys.  Chem.,  i,  636  (1897). 

81  BANCROFT,  Jour.  Phys.  Chem.,  21,  591   (1917). 

52  Berichte,  37,  2986  (1904). 

68  Jour.  Am.  Chem.  Soc.,  34,  911  (1912). 


180h  CATALYSIS  IN  ORGANIC  CHEMISTRY  62 

excess  of  the  adsorbed  reaction  product  should  cut  down  the  rate  of 
reaction  and  that  is  the  case.  When  working  at  high  pressures,  the 
first  stage  in  the  dehydration  of  alcohol  in  presence  of  heated  alumina 
is  the  production  of  ether.  When  an  equimolecular  mixture  of  ether 
and  water  is  passed  over  alumina  at  400°,  practically  no  ethylene  is 
formed.54  Engelder  55  showed  that  presence  of  water  vapor  decreased 
very  markedly  the  rate  of  decomposition  of  ethyl  alcohol  by  alumina. 
Titania  causes  alcohol  to  split  both  into  acetaldehyde  and  hydrogen 
and  into  ethylene  and  water.  Engelder  showed  that  addition  of 
hydrogen  to  the  alcohol  vapor  increased  the  relative  yield  of  ethylene 
and  addition  of  water  vapor  increased  the  relative  yield  of  acetalde- 
hyde, though  the  difference  was  not  as  marked  as  one  might  have 
wished.  A  somewhat  similar  result  appears  to  have  been  obtained 
unconsciously  by  Berthelot  56  fifty  years  ago.  He  heated  formic  acid 
at  260°  without  any  specified  catalytic  agent  and  found  that  when 
only  a  third  of  the  formic  acid  is  decomposed  the  reaction  appears 
to  be 

HC02H  =  CO  +  H20. 

If  all  the  formic  acid  is  decomposed,  the  reaction  is  approximately 

2  HC02H  =  CO  +  H20  +  C02  +  H2. 
This  unexpected  result  can  only  be  true  in  case  the  reaction 

HC0H  =  C0       H2 


predominates  during  the  latter  part  of  the  decomposition  and  this 
can  happen  only  in  case  the  original  decomposition  products  check 
the  initial  reaction  and  thus  permit  the  second  reaction  to  come  to 
the  fore.  The  experiments  by  Berthelot  should  be  repeated  so  as  to 
make  sure  that  they  are  right  and  that  the  suggested  explanation  is 
the  true  one. 

180h.  While  this  seems  very  satisfactory,  there  are  certain  points 
which  must  not  be  overlooked.  When  making  ethylene  at  Edgewood 
Arsenal  during  the  war,  it  was  found  advisable  to  have  a  large  amount 
of  steam  present  with  the  alcohol  vapor  in  order  to  make  temperature 
regulation  easier.  This  undoubtedly  decreased  the  rate  of  decompo- 
sition of  the  alcohol;  but  that  difficulty  was  overcome  by  working  at 
a  higher  temperature.  I  find  it  very  difficult  to  see  how  alumina  can 
dehydrate  alcohol  in  presence  of  a  large  amount  of  water  vapor  if 
the  reason  the  alumina  acts  is  because  of  its  strong  adsorption  of 
water  vapor.  In  spite  of  the  fact  that  the  theory  of  the  selective 

6*  IPATIEF,  Berichte,  37,  2996  (1904). 

55  Jour.  Phys.  Chem.,  21,  676  (1917). 

66  Ann.  Chim.  Phys.,  (4),  18,  42  (1869). 


63  THE  MECHANISM  OF  CATALYSIS  180j 

adsorption  of  the  reaction  products  undoubtedly  contains  a  great 
amount  of  truth,  it  must  be  admitted  that,  as  now  formulated,  it  is 
not  the  final  word.  It  must  be  modified  before  it  can  be  considered 
as  satisfactory.  If  it  breaks  down  temporarily  in  the  simple  case 
of  the  decomposition  of  alcohol,  it  is  not  surprising  that  we  cannot  as 
yet  predict  the  decompositions  of  the  esters  by  means  of  it. 

180i.  The  whole  problem  of  catalysis  has  been  put  in  a  general 
but  vague  form  by  Baly  and  Krulla  and  Baly  and  Rice57  who  con- 
sider that  we  have  a  partial  conversion  of  one  or  more  reacting  sub- 
stances into  active  forms  through  opening  up  fields  of  force  by  the 
rupture  of  normal  valence  or  of  contra-valences.  The  trouble  with 
this  is  that  it  is  as  yet  too  vague  to  be  of  much  value  as  a  working 
hypothesis,  though  it  makes  an  admirable  starting-point.  Methods 
must  be  devised  for  showing  in  each  particular  case  what  particular 
valences  or  contra-valences  are  ruptured  as  a  preliminary  step  in 
the  reaction. 

180j.  The  radiation  theory  postulates  that  the  catalytic  agent 
emits  radiations  which  convert  one  or  more  of  the  reacting  substances 
into  active  modifications.  Miss  Woker  58  has  given  a  sketch  of  the 
earlier  speculations  as  to  radiation.  The  only  one  which  has  sur- 
vived is  that  of  Barendrecht,59  and  his  calculations  have  been 
criticized  severely  by  Henri.60  Kriiger61  has  attempted  to  account 
for  a  number  of  phenomena  in  homogeneous  solutions  by  postulating 
infra-red  radiation.  This  idea  has  been  developed  by  W.  C.  McC. 
Lewis62  and  applied  to  the  change  of  reaction  velocity  with  the 
temperature  and  to  contact  catalysis.  More  recently,  Pen-in63  has 
put  forward  similar  views  without  making  any  reference  to  the  work 
of  others.  Lewis  believes  that  the  catalytic  agents  emit  infra-red 
rays  which  activate  the  reacting  substance.  This  would  seem  to 
make  it  possible  for  a  catalytic  agent  to  act  at  a  distance;  but  this 
difficulty  can  be  avoided  by  assuming  that  the  intensity  of  the  infra- 
red radiation  is  so  low  that  it  is  effective  only  when  the  distances 
are  molecular.  An  interesting  case  comes  up  in  homogeneous  solu- 

57  Jour.  Chem.  Soc.,  101,  1469,  1475  (1912). 
«  Die  Katalyse,  p.  60  (1910). 

59  Zeit.  phys.  Chem.,  49,  456  (1904);  54,  367  (1906);  Proc.  Ron.  Akad.  Wet. 
Amsterdam,  22,  29  (1919). 

eo  Zeit.  phys.  Chem.,  51,  19   (1905). 

61  Zeit.  Elektrochemie,  17,  453  (1911). 

62  Jour.  Chem.  Soc.,  105,  2330   (1914);    107,  233  (1915);   109,  55,  67,  796 
(1916);   in,  457,  1036  (1917);   113,  471   (1918);   115,  182   (1919);  System  of 
Physical  Chemistry,  3,  138  (1919). 

63  PERRIN,  Ann.  Physique,  (9),  u,  5  (1919). 


180k  CATALYSIS  IN  ORGANIC  CHEMISTRY  64 

tions.  Methyl  acetate  has  a  strong  absorption  band  between  5/w. 
and  11 /A  the  hydrogen  ion  is  supposed  to  emit  wave-lengths  over 
the  range  1.1-11  ft,  and  hydrogen  ion  catalyzes  methyl  acetate 
solutions.  Professor  Rideal  of  the  University  of  Illinois  has  shown 
that  infra-red  radiations  corresponding  to  the  absorption  band  of 
methyl  acetate  do  accelerate  the  reaction  between  methyl  acetate  and 
water;  but  this  would  happen  on  any  hypothesis.  It  has  not  been 
shown  that  the  catalytic  action  of  the  infra-red  rays  supposed  to  be 
emitted  by  hydrogen  ion  corresponds  quantitatively  with  the  catalytic 
action  of  the  hydrogen  ion.  This  might  be  a  difficult  thing  to  estab- 
lish to  the  satisfaction  of  the  doubters ;  but  there  is  a  test  which  would 
probably  be  accepted  as  crucial  by  everybody.  Heated  nickel  de- 
composes ethyl  acetate  into  propane  and  carbon  dioxide;  heated 
thoria  converts  it  into  acetone,  ethyl  alcohol,  ethylene  and  carbon 
dioxide;  while  heated  titania  changes  it  into  acetic  acid  and 
ethylene.64  If  somebody  would  produce  these  three  sets  of  reactions 
separately  by  means  of  infra-red  radiations  with  no  catalytic  agent 
present,  the  radiation  theory  would  have  a  standing  which  it  does  not 
have  at  present.  Since  alumina  is  very  permeable  to  infra-red  radia- 
tions and  ferrous  oxide  is  not,65  the  latter  should  be  a  very  efficient 
catalytic  agent  according  to  the  radiation  theory.  This  has  not  been 
tested  so  far  as  I  know.  Tyndall 66  states  that  gum  arabic  is  prac- 
tically impermeable  to  infra-red  radiations.  If  this  is  true,  gum 
arabic  should  catalyze  the  hydrolysis  of  methyl  acetate  enormously 
if  the  radiation  theory  is  sound. 

180k.  This  brief  sketch  of  the  theories  of  contact  catalysis  shows 
how  unsatisfactory  our  present  knowledge  is.  This  is  due  to  the  in- 
accurate and  incomplete  way  in  which  the  single  reactions  have  been 
studied.  We  do  not  know  which  cases  involve  definite  intermediate 
compounds  and  which  do  not.  When  we  are  agreed  that  definite 
intermediate  compounds  are  formed,  we  do  not  agree  as  to  their 
nature.  We  talk  about  breaking  normal  valences  or  contra-valences ; 
but  we  do  not  specify  which  valences  or  which  contra-valences. 
When  ethyl  alcohol  is  decomposed  by  pulverulent  nickel  into  acetal- 
dehyde  and  hydrogen,  does  molecular  hydrogen  split  off  or  do  the  two 
hydrogens  come  off  separately?  If  the  latter  happens  does  the  first 
hydrogen  come  from  the  hydroxyl  group  or  not?  When  ethyl  alcohol 
is  decomposed  by  alumina  into  ethylene  and  water,  does  water,  hydro- 
gen, or  hydroxyl  come  off  first?  It  can  hardly  be  water  because  it 
is  possible  to  stop  the  reaction  at  the  intermediate  stage  of  ether, 

64  SABATIEB  and  MAILHE,  Compt.  rend.,  152,  669  (1911). 

65  ZSIGMONDY,  Dingler's  Poly  tech.  Jour.,  (6),  37,  17,  68,  108;  39,  237  (1893). 

66  Fragments  of  Science:   Radiant  Heat  and  its  Relations. 


65  THE  MECHANISM  OF  CATALYSIS  180n 

and  it  is  probably  not  monatomic  hydrogen  because  that  is  what 
happens  with  nickel.  If  the  first  stage  is  a  splitting  off  of  hydroxyl, 
does  the  other  hydrogen  come  from  the  adjacent  carbon  atom  giving 
ethylene  direct  or  does  it  come  from  the  same  carbon  atom,  forming 
a  substituted  methylene,  CH3CH,  which  then  rearranges  to  ethylene? 
The  decomposition  of  ether  by  alumina  apparently  must  lead  to 
2  CH3CH  +  H20  as  one  of  the  intermediate  stages.  How  does 
nickel  decompose  ether? 

1801.  In  at  least  two  instances  it  should  be  relatively  simple  to 
determine  the  reacting  radicals.  If  we  pass  a  mixture  of  ethyl  ace- 
tate and  hydrogen  over  pulverulent  nickel,  it  is  probable  that  some 
or  all  of  the  initial  products  will  be  reduced  before  they  have  time 
to  react  in  the  normal  way.  A  study  of  the  reaction  products  will 
therefore  throw  light  on  the  probable  mechanism  of  the  reaction 
which  occurs  in  the  absence  of  hydrogen.  If  we  obtained  CH4  and 
HC02C2H5,  for  instance,  we  should  conclude  that  the  original  break 
had  been  into  CH3  and  C02C2H5.  If  we  found  CH3C02H  and  C2H6, 
we  should  conclude  that  these  were  reduction  products  of  CH3C02 
and  C2H5.  If  the  reaction  products  were  CH4,  C2H6,  and  C02  or 
some  reduction  product  of  this  last,  we  should  undoubtedly  assume 
that  ethyl  acetate  splits  simultaneously  into  CH3,  C02  and  C2H5. 

180m.  If  ether  is  passed  over  pulverulent  nickel,  the  dissociation 
will  probably  be  to  C2H50  +  C2H5  or  to  C2H50  +  C2H4  +  H.  In 
the  first  case  the  final  products  will  be  2  C2H4  and  H20  just  as  with 
alumina.  In  the  second  case  they  are  likely  to  be  CH3CHO  +  C2H4 
+  H2,  though  the  ethylene  and  hydrogen  may  combine  more  or  less 
completely  to  form  ethane. 

180n.  These  two  illustrations  are  sufficient  to  indicate  the  kind 
of  work  that  ought  to  be  done  and  the  organic  chemists  will  un- 
doubtedly be  able  to  develop  this  suggestion  in  most  unexpected  ways. 

The  following  cases  are  worth  considering,  though  it  must  not  be 
assumed  that  the  reactions  run  as  written  for  one  hundred  per  cent 
yield. 

With  nickel  we  get  the  following  decompositions  of  the  esters: 

CH3C02CH2CH3  —  CH3CH2CH3  +  C02 
CH3C02CH3  —  CH3CH3  +  C02 
HC02CH3  =  CH4(?)  +  C02 

With  thoria  the  decomposition  is  quite  different: 

2  CH3C02CH2CH3  —  CH3COCH3  +  C02  +  (C2H5)20 

—  CH3COCH3  +  C02  +  C2H5OH  +  C2H4 
2  CH3C02CH3  -  CH3COCH3  +  C02  +  (CH3)20 
2  HC02CH3  =  ECHO  +  C02  +  (CH3)20 


180o  CATALYSIS  IN  ORGANIC  CHEMISTRY  66 

With  titania  there  is  a  third  set  of  products: 

CH3C02CH2CH3  =  CH3C02H  +  C2H4 
2  CH3C02CH3  =  2CH3C02H  +  C2H4 

HCO2CH3  =  HCO2H  +  CH2  =  CO  +  CH3OH. 

The  decompositions  are  regular  and  characteristic  with  each  catalytic 
agent  and  the  molecules  must  break  or  slip  at  different  points  in  the 
different  cases.  It  would  help  a  great  deal  towards  formulating  a 
theory  of  the  behavior  of  these  oxides  if  we  knew  exactly  what  hap- 
pened in  each  case.  Of  course,  a  study  of  this  sort  should  include 
the  chlorinated  esters.  There  is  some  evidence  to  show  that  the  de- 
composition may  shift  from  one  type  to  another  with  increasing  sub- 
stitution of  hydrogen  by  chlorine. 

180o.  While  we  have  no  satisfactorily  developed  theories  of  con- 
tact catalysis  at  present,  our  theoretical  knowledge  in  regard  to  the 
poisoning  of  catalytic  agents  is  in  good  shape,  though  it  is  not  sup- 
ported as  yet  by  adequate  experimental  evidence.  Since  the  reaction 
takes  place  in  or  at  the  surface,  it  follows  that  any  substance,  which 
cuts  down  the  rate  at  which  the  reacting  substances  reach  the  cat- 
alytic surface  67  or  which  prevents  them  from  reaching  it,  will  decrease 
the  reaction  velocity  and  may  destroy  the  catalytic  action  entirely. 
Berliner 68  has  shown  that  traces  of  fatty  vapors  from  the  air  or  from 
the  grease  on  the  stop- cocks  will  decrease  the  adsorption  of  hydrogen 
by  palladium  from  nearly  nine  hundred  volumes  practically  to  noth- 
ing. Faraday  69  has  shown  that  traces  of  grease  destroy  the  catalytic 
action  of  platinum  on  oxyhydrogen  gas.  De  Hemptinne  70  has  appar- 
ently shown  that  carbon  monoxide  cuts  down  the  adsorption  of  hydro- 
gen by  palladium,  though  his  method  of  presenting  his  results  is  very 
obscure.  Harbeck  and  Lunge  71  found  that  carbon  monoxide  inhibits 
practically  completely  the  catalytic  action  of  platinum  on  a  mixture 
of  ethylene  and  hydrogen.  Schonbein  72  pointed  out  that  the  hydrides 
of  sulphur,  tellurium,  selenium,  phosphorus,  arsenic,  and  antimony 
act  very  energetically  in  cutting  down  the  catalytic  action  of  platinum 
on  mixtures  of  air  with  hydrogen  or  ether.  He  considered  that  the 
hydride  must  decompose,  giving  rise  to  a  solid  film.  This  is  not 
necessary  in  order  to  account  for  the  phenomenon;  but  he  seems  to 
have  been  right  in  at  least  one  case,  for  Maxted 73  has  found  that 

67  TAYLOR,  Trans.  Am.  Electrochem.  Soc.,  36  (1919). 
«*  Wied.  Ann.,  35,  903  (1888). 

69  Experimental  Researches  on  Electricity,  i,  185  (1839). 

70  Zeit.  phys.  Chem.,  27,  249  (1898). 

71  Zeit.  anorg.  Chem.,  16,  50  (1898). 

72  Jour,  prakt.  Chem.,  29,  238  (1843). 

73  Jour.  Chem.  Soc.,  115,  1050  (1919). 


67  THE  MECHANISM  OF  CATALYSIS  180r 

hydrogen  sulphide  is  decomposed  by  platinum  black  with  evolution 
of  hydrogen,  and  that  the  platinum  then  does  not  adsorb  hydrogen. 
Paal  and  Hartmann 74  state  that  the  catalytic  action  of  palladium 
hydrosol  and  its  adsorption  of  hydrogen  are  destroyed  by  metallic 
mercury  or  by  the  oxide  of  mercury. 

180p.  Langmuir 75  believes  that  oxygen  prevents  dissociation 
of  hydrogen  by  a  heated  tungsten  filament  because  it  cuts  down  the 
adsorption  of  the  hydrogen. 

180q.  Harned  76  has  shown  that  the  rate  of  adsorption 77  of  chlor- 
picrin  by  a  charcoal  which  has  been  cleaned  by  washing  with 
chlorpicrin  is  much  greater  at  first  than  by  a  charcoal  which  has  not 
been  so  cleaned,  although  the  final  equilibrium  is  apparently  about 
the  same  in  the  two  cases.  This  is  analogous  to  the  evaporation  of 
water  when  covered  by  an  oil  film.  The  oil  cuts  down  the  rate  of 
evaporation  very  much  but  has  practically  no  effect  on  the  partial 
pressure  of  water  at  equilibrium.  Taylor  points  out  that  normally 
the  time  of  contact  between  a  gas  and  the  solid  catalytic  agent  is 
extremely  small  and  consequently  anything  which  decreases  the  rate 
of  adsorption  will  cut  down  the  reaction  velocity  very  much. 

180r.  It  is  easy  to  see  that  the  piling  up  of  the  reaction  products 
will  cut  down  the  reaction  velocity,  if  they  prevent  the  reacting  sub- 
stances from  coming  in  contact  with  the  catalytic  agent.  Bunsen 
apparently  recognized  this  as  early  as  1857  for  he  is  quoted  78  as 
saying  that  it  is  only  when  the  products  of  decomposition  are  removed 
and  new  matter  is  brought  into  contact  that  the  reaction  continues. 
This  has  been  observed  experimentally  in  the  contact  sulphuric  acid 
process.79  The  explanation  that  the  decrease  in  the  reaction  velocity 
is  due  to  a  decreased  adsorption  of  the  reacting  substances  was  first 
given  by  Fink,80  who  is  the  real  pioneer  in  this  line.  Although  the 
reaction  between  carbon  monoxide  and  oxygen  is  practically  irre- 
versible at  ordinary  temperature,  Henry  81  recognized  that  the  pres- 
ence of  the  reaction  product  might  slow  up  the  rate  of  reaction  and 
he  proved  his  point  by  increasing  the  reaction  velocity  when  he  re- 
moved the  carbon  dioxide  with  caustic  potash.  Water  vapor  checks 

74  Berichte,  51,  711  (1918). 

76  Jour.  Am.  Chem.  Soc.,  38,  2272  (1916). 

76  Jour.  Am.  Chem.  Soc.,  42,  372  (1920). 

77  TAYLOR,  Trans.  Am.  Electrochem.  Soc.,  36   (1919). 

78  DEACON,  Jour.  Chem.  Soc.,  25,  736  (1872). 

79  BODLANDER  and  KOPPEN,  Zeit.  Elektrochemie,  9,  566  (1903);  BERL,  Zeit. 
anorg.  Chem.,  44,  267  (1905). 

80  BODENSTEIN  and  FINK,  Zeit.  phys.  Chem.,  60,  61  (1907). 

81  Phil  Mag.    (3),  9,  324  (1836). 


180s  CATALYSIS  IN  ORGANIC  CHEMISTRY  68 

the  catalytic  dehydration  of  ether82  and  of  alcohol83  and  hydrogen 
cuts  down  the  catalytic  dehydrogenation  of  alcohol. 

180s.  When  catalytic  poisons  are  present  or  are  formed  during  the 
reaction,  the  apparent  equilibrium  may  vary  with  the  amount  of  the 
catalytic  agent.84  With  only  a  small  amount  present,  the  catalytic 
agent  will  be  poisoned  before  the  reaction  has  run  very  far.  In  the 
hydrolysis  of  ethyl  butyrate  by  enzymes,  the  reaction  apparently 
runs  to  different  end-points  depending  on  the  relative  amounts  of 
enzyme.85 

While  our  theoretical  knowledge  in  regard  to  the  poisoning  of 
catalytic  agents  is  fairly  adequate,  we  know  literally  nothing  except 
empirically  in  regard  to  the  action  of  the  so-called  promoters.  It  has 
recently  been  found  that  the  addition  of  small  amounts  of  a  substance 
which  does  not  in  itself  have  any  very  marked  catalytic  action  may 
make  the  catalyst  considerably  more  active.  Such  substances  were 
called  promoters  in  the  patents  of  the  Badische  Anilin  and  Soda 
Fabrik,  and  the  term  is  now  in  common  use.  Rideal  and  Taylor  say: 
"  Thus  far  no  theory  put  forward  to  account  for  the  acceleration  of 
reaction  by  minute  quantities  of  promoters  added  to  the  main  catalyst 
material  is  completely  satisfactory.  A  possible  mechanism,  which, 
however,  has  received  no  experimental  test,  may  be  advanced  by  con- 
sidering the  case  of  ammonia  synthesis  from  mixtures  of  nitrogen  and 
hydrogen.  Reduced  iron  is  an  available  contact  substance,  the  ac- 
tivity of  which  may  be  regarded  as  due  to  the  simultaneous  formation 
of  the  compounds,  hydride  and  nitride,  with  subsequent  rearrangement 
to  give  ammonia  and  unchanged  iron.  Or,  maybe,  the  activity  of  the 
iron  is  due  to  simultaneous  adsorption  of  the  two  gases.  The  par- 
ticular mechanism  of  the  catalysis  is  unimportant  for  the  present 
considerations.  Now  such  bodies  as  molybdenum,  tungsten,  and 
uranium  have  been  proposed,  among  others,  as  promoters  of  the  ac- 
tivity of  iron.  It  is  conceivable  that  these  act  by  adjusting  the  ratio 
in  which  the  elementary  gases  are  adsorbed  by  or  temporarily  com- 
bined with  the  catalytic  material  to  give  a  ratio  of  reactive  nitrogen 
and  hydrogen  more  nearly  that  required  for  the  synthesis,  namely, 
one  of  nitrogen  to  three  of  hydrogen.  From  the  nature  of  the  ma- 
terials suggested  as  promoters,  it  would  seem  that  they  are  in  the 
main  nitride-forming  materials,  which  on  the  above  assumption  of 
mechanism  would  lead  to  the  conclusion  that  the  original  iron  tended 

82  IPATIEF,  Berichte,  37,  2996  (1904). 

88  LEWIS,  Jour.  Chem.  Soc.,  115,  182  (1919). 

8*  BANCROFT,  Jour.  Phys.  Chem.,  22,  22  (1918). 

85  KASTLE  and  LOEVENHART,  Am.  Chem.  Jour.,  24,  491   (1900). 


69  THE  MECHANISM  OF  CATALYSIS  180u 

to  adsorb  or  form  an  intermediate  compound  with  a  greater  propor- 
tion of  hydrogen  to  nitrogen  than  required  by  the  stoichiometric  ratio. 
The  catalytic  activity  of  reduced  iron  as  a  hydrogenation  agent  would 
tend  to  confirm  this  viewpoint. 

180t.  "  In  reference  to  this  suggested  mechanism  it  must  be 
emphasized,  however,  that  in  such  examples  of  '  promotion,'  as  re- 
quire only  minute  quantities  of  added  promoter  the  activity  is  more 
difficult  to  understand.  With  the  case  of  ammonia  synthesis,  the 
promoters  are  added  in  marked  concentrations.  It  is  difficult  to 
realize,  however,  that  0.5  per  cent  of  ceria  or  a  concentration  of  one 
molecule  of  ceria  among  200  molecules  of  iron  oxide,  in  the  example 
cited  above  in  reference  to  catalytic  hydrogen  production,  can  so  far 
'  redress  the  balance '  of  adsorption  or  combination  as  to  produce  the 
marked  increase  in  activity  of  which  it  is  capable.  It  is  obvious  that 
in  this  phase  of  the  problem  there  lies  an  exceedingly  fascinating  field 
for  scientific  investigation,  with  the  added  advantages  that,  being 
practically  virgin  territory,  the  harvest  to  be  gained  therefrom  should 
be  rich  and  abundant." 

180u.  Instead  of  the  promoter  changing  the  ratio  of  adsorption, 
it  might  be  that  the  catalytic  agent  activates  only  one  of  the  reacting 
agents  or  activates  one  chiefly,  and  that  the  promoter  activates  the 
other.  Thus  it  might  be,  in  the  ammonia  synthesis,  that  iron  acti- 
vates the  hydrogen  chiefly  so  that  we  have  hydrogenation  of  the 
nitrogen.  The  molybdenum  might  tend  to  activate  the  nitrogen 
giving  rise  to  nitridation  of  hydrogen,  or  it  might  increase  the  activa- 
tion of  the  nitrogen.  Such  a  state  of  things  is  not  impossible  theo- 
retically. When  a  dye  reacts  with  oxygen  under  the  influence  of 
light,  the  light  may  make  the  oxygen  active,  in  which  case  the  acti- 
vated oxygen  oxidizes  the  dye,  or  the  light  may  make  the  dye  active 
in  which  case  the  activated  dye  reduces  the  oxygen.  It  is  easy  to 
decide  this  question  by  seeing  whether  the  effective  light  corresponds 
to  an  adsorption  band  for  the  dye  or  for  the  oxygen. 


CHAPTER  IV 

ISOMERIZATIONS,    POLYMERIZATIONS,    AND 
CONDENSATIONS    BY   ADDITION 

§  i.     ISOMERIZATIONS 

181.  ISOMERIZATIONS,  that  is  to  say,  changes  of  structure  effected 
within   a   molecule   without   modifying   its    composition,    are    often 
accomplished  by  the  action  of  heat  alone. 

As  catalysts  have  frequently  the  effect  of  lowering  the  temperature 
of  reactions,  it  can  be  foreseen  that  their  use  will  permit,  in  many 
cases,  of  realizing  an  isomerization  at  a  lower  temperature,  or  causing 
it  to  go  more  rapidly.  Experiment  has  often  verified  this  prediction 
under  very  varied  conditions. 

Strong  mineral  acids  bring  about  a  large  number  of  isomerizations ; 
the  concentration  of  the  acid  has  usually  a  great  influence  on  the 
direction  of  the  transformation.  The  mechanism  of  the  change  can 
usually  be  interpreted  by  assuming  the  addition  of  water  to  the 
original  compound  under  the  influence  of  the  acid  ions  followed  by  a 
dehydration,  or  the  reverse. 

182.  Change    of    Geometric    Isomers.     The    transformation    of 
fumaric  acid  into  maleic  is  brought  about  by  a  large  number  of  cat- 
alysts, for  example  hydrobromic  or  hydriodic  adds  in  hot  concen- 
trated solution,1  hot  hydrochloric  acid,2  or  hot  dilute  nitric  acid.3 

Bromine  acts,  in  the  cold,  on  maleic  acid  to  give  dibromsuccinic 
acid  but,  at  the  same  time,  a  part  of  the  maleic  acid  is  changed  to 
fumaric.4 

Likewise,  traces  of  iodine  are  sufficient  to  transform  maleic  esters 
into  fumaric.6 

If  to  a  solution  of  maleic  acid  an  equivalent  amount  of  sodium 
thiosulphate  be  added  and  then  sulphuric  acid,  sulphur  dioxide  is 
evolved  without  appreciable  separation  of  sulphur  and  25%  of  fumaric 
acid  crystallizes  out.6 

1  KEKULE,  Annalen,  Supp.  Band,  i,  133  (1861). 

2  KEKULE^  and  STRECKER,  Annalen,  223,  186  (1884). 

3  KEKUL&,  Annalen,  Supp.  Band,  2,  93  (1862). 

4  PETRI,  Annalen,  195,  49  (1879). 

5  SKRAUP,  Monatsh.,  12,  107  (1891). 

6  TANATAR,  /.  Russian  Phys.  Ghent.  Soc.,  43,  1742  (1912),  C.  A.,  6,  1279. 

70 


71  CONDENSATIONS  BY  ADDITIONS  186 

When  hydrogen  sulphide  is  passed  into  solutions  of  lead,  copper, 
or  cadmium  maleates,  the  maleic  acid  set  free  is  changed  to  fumaric.7 

183.  Citraconic  acid  warmed  with  dilute  nitric  acid,8  or  with  con- 
centrated hydrobromic  acid*  or  with  concentrated  hydriodic  acid,™ 
is  changed  into  mesaconic  acid. 

Warmed  above  100°  with  a  concentrated  solution  of  caustic  soda, 
it  gives  mesaconic  acid  with  a  little  itaconic.^ 

Itaconic  acid  dissolved  in  a  mixture  of  ether  and  chloroform  to 
which  a  few  drops  of  a  chloroform  solution  of  bromine  have  been 
added,  and  exposed  to  sunlight,  is  transformed  into  mesaconic  acid.12 

Itaconic  acid  boiled  with  soda  lye  changes,  almost  entirely,  into 
mesaconic.13 

184.  Small  amounts  of  nitrous  acid  transform  a  number  of  cis 
ethylenic  acids  into  their  trans  isomers,  ole'ic  into  elaidic,14  hyprogaeic 
into  gaidic,™  erucic,  C8H17CH  :  CHICHJ^CC^H,  into  brassidic.1* 

185.  a-Benzaldoxime  in  contact  with  hydrogen  chloride  or  with 
crystallized  pyrosulphuric  acid  is   changed  into     p-benzaldoxime.17 
The  reverse  change  is  brought  about  by  contact  with  dilute  sulphuric 
acid. 

186.  Changes  of  Optical  Isomers.     Solutions  of  caustic  soda  can 
determine  numerous  stereo-isomeric  changes  in  the  sugar  group  and 
the  same  is  true  of  solutions  of  lime  and  baryta  and  even  of  pure 
water  mixed  with  lead  and  zinc  hydroxides.18     Glucose,  mannose  and 
fructose,  heated  two  hours  under  these  conditions  yield  the  same  mix- 
ture of  these  three  hexoses.    In  the  cold  and  with  concentrated  alka- 
lies, the  same  isomerization  takes  place  in  five  days.    In  the  same 
way,  galactose  gives  a  mixture  of  sorbose,  tagatose,  talose  and  gal- 
tose.18    Similarly  baryta  water  transforms  gulose  or  idose  into  sor- 


7  SKRAUP,  loc.  cit. 

8  GOTTLIEB,  Annalen,  77,  268  (1857). 

9  FITTIG,  Ibid.,  188,  77  and  80  (1877). 

10  KEKULE,  Ibid.,  SupL,  2,  94  (1862). 

11  DELISLE,  Ibid.,  269,  82  (1892).    FITTIG  and  LANGWORTHY,  Ibid.,  304,  152 
(1899). 

12  FITTIG  and  LANGWORTHY,  Ibid.,  304,  152  (1899). 

13  FITTIG  and  KOHL,  Ibid.,  305,  41  (1899). 

14  BOUDET,  Ann.  Chim.  Phys.  (2),  50,  391  (1832).    LAURENT,  Ibid.  (2),  65, 
149  (1837). 

15  CALDWELL  and  GOSSMANN,  Annalen,  99,  307  (1856). 
!6  HAUSSKNECHT,  Ibid.,  143,  54  (1867). 

17  BECKMANN,  Berichte,  20,  2766  (1887). 

18  LOBRY  DE  BRUYN  and  VAN  EKENSTEIN,  Rec.  Trav.  Chim.  Pays-Bos,  14, 
203  (1895)  and  15,  92  (1896). 

19  VAN  EKENSTEIN  and  BLANKSMA,  Ibid.,  27,  1  (1908). 


187  CATALYSIS  IN  ORGANIC  CHEMISTRY  72 

187.  The  acids  derived  from  the  hexoses  are  isomerized  when  they 
are  heated  to  135-150°  with  an  organic  base  that  does  not  yield 
amides  with  the  acids;  quinoline  or  pyridine  are  usually  employed. 
The  new  acid  differs  from  the  old  only  in  the  arrangement  of  the 
groups  around  the  last  asymmetric  carbon  atom.    Furthermore,  the 
isomerizations  take  place  in  both  directions,  reaching  the  same  limit. 
Thus  gluconic  acid  furnishes  mannonic  with  quinoline  and  recipro- 
cally.20   Likewise  with  pyridine  we  pass  from  arabonic  acid  (with  five 
carbon  atoms)  to  ribonic,21  from  lyxonic  to  xylonic22  and  also  from 
the  dibasic  acid,  talomucic,  to  mucic2* 

188.  The    sugars,    glucose,    laevulose,    galactose,    arabinose,    and 
xylose,  which  are  not  susceptible  of  a  molecular  decomposition  by  the 
addition  of  water,  present  a  special  phenomenon  known  as  multirota- 
tion;  the  rotatory  power  observed  immediately  after  solution  in  water 
is  much  greater  than  that  after  some  tune.24 

Thus  the  rotation  of  glucose  starts  at  105°  and  goes  down  to  half 
of  this,  52.50.25  The  explanation  is  that  there  are  isomeric  molecular 
modifications  of  these  various  sugars,  analogous  to  the  three  varieties 
that  Tanret  has  been  able  to  isolate  for  glucose.26 

Of  the  three  varieties,  the  one  that  is  stable  in  dilute  solution, 
called  /?,  has  exactly  the  rotatory  power  finally  found,  52.5°,  another 
form  a  has  the  value  106°.  The  passage  to  the  stable  isomer  takes 
place  slowly  in  the  cold,  rapidly  when  hot,  but  is  greatly  accelerated 
by  the  presence  of  mineral  acids.™ 

189.  dMenthone  on  long  contact  with  sulphuric  acid  containing 
10%  of  its  volume  of  water  passes  to  Lmenthone2* 

190.  Migrations    of    Double    and    Triple    Bonds.    Isopropyl- 
ethylene,  (CH3)2CH .  CH  :  CH2,  when  heated  under  pressure  at  480- 
500°   in  the  presence  of  anhydrous  alumina,  is  transformed   into 
trimethyl-ethylene,  (CH3)2C  :  CH  .  CH3.29 

191.  Eugenol,  when  boiled  with  amyl  alcoholic  potash,  changes 
to  isoeugenol,  the  direct  oxidation  of  which  furnishes  vanilline:  30 

2°  E.  FISCHER,  Berichte,  23,  801  (1890). 

21  FISCHER  and  PILOTY,  Berichte,  24,  4216  (1891). 

22  FISCHER  and  BROMBERG,  Berichte,  29,  584  (1896). 
28  FISCHER  and  MORELL,  Berichte,  27,  387  (1894). 

2*  DUBRUNFAUT,  Ann.  Chim.  Phys.    (3),  18,  105  (1846). 

28  PARCUS  and  TOLLENS,  Annalen,  257,  160  (1890). 

2«  TANRET,  Bull.  Soc.  Chim.  (3),  15,  195  and  349  (1896). 

27  ERDMANN,  Jahresb.,  1855,  672. 

2*  BECKMANN,  Annalen,  250,  334  (1889). 

29  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  38,  63  and  92  (1906),  C.,  1906,  (2), 
86  and  87. 

80  TIEMANN,  Berichte,  24,  2871  (1891). 


73  CONDENSATIONS  BY  ADDITIONS  193 


,         CH  :  CH2  ,CH  :  CH  -  CH, 

C6H3  -  OCH,        ->        C6H3  -  OCHs 


\)H  \) 


H 

192.  The  acetylene  triple  bond  undergoes  analogous  transpositions 
under  the  influence  of  sodium  or  of  alkalies. 

Ethyl-acetylene,  CH3  .  CH2  .  C  i  CH,  heated  with  potash  to  170°, 
changes  to  dimethyl-acetylene,  CH3  .  C  i  C  .  CH3.  31 

Inversely,  disubstituted  acetylene  hydrocarbons  are  changed 
into  true  acetylenes  when  they  are  heated  with  sodium,  a 
part  of  the  new  hydrocarbon  combining  with  the  metal, 
e.  g.  methyl-ethyl-acetylene,  CH3  .  C  •  C  .  CH2  .  CH3,  gives  propyl- 
acetylene,  CH3  .  CH2  .  CH2  .  C  i  CH.32 

The  same  catalysts  cause  the  transformation  of  allenic  hydro- 
carbons into  acetylene  hydrocarbons  and  inversely.  Thus  diethyl- 
allene,  CH3  .  CH2  .  CH  :  C  :  CH  .  CH2  .  CH3,  which  under  the  influ- 
ence of  heat  alone  isomerizes  into  methyl-ethyl-butadiene,  is  changed 
by  contact  with  metallic  sodium  into  diethyl-allylene,  CH3  .  CH2,- 
CH2.C  !  C.CH2.CH3.  33 

Inversely  isopropyl-acetylene,  (CH3)2CH  .C  i  CH,  heated  above 
150°  with  alcoholic  potash,  changes  to  dimethyl-allene,  (CH3)2C  :- 
C  :  CH2.  34 

193.  Decyclizations.    Cyclo-propane  is  not  changed  to  propylene 
by  heat  alone  below  600°,  but  in  the  presence  of  platinum  sponge,  this 
change  takes  place  in  the  cold  and  very  rapidly  at  100°.  35 

The  vapors  of  ethyl-cyclo-propane  passed  at  300-310°  over  as- 
bestos impregnated  with  anhydrous  alumina,  are  isomerized  into 
methyl-ethyl-ethylene  : 

v 

;CH.CH2.CH3   -»  CH3  .  CH  :  CH  .  CH2  .  CH3.  36 
/ 

CH2v 

Methylene-cyclo  -propane,    \         C  :  CH2,  passed  over  alumina  at 

CH/ 
350°,  gives  divinyl,  CH2  :  CH  .  CH  :  CH2.  37 

81  FAWORSKII,  J.  Russian  Phys.  Chem.  Soc.,  19,  414  and  553  (1887)  ;  ao,  518 
(1888),  C.,  1887,  153. 

32  FAWORSKY,  /.  prakt.  Chem.,  (2),  37,  387  (1888).  B^HAL,  Butt.  Soc.  Chim., 
50,  629  (1888). 

88  MERESHKOVSKI,  J.  Russian  Phys.  Chem.  Soc.,  45,  1969  (1914),  C.  A.,  8, 
1420. 

84  FAWORSKY,  /.  prakt.  Chem.   (2),  37,  392  (1888). 

88  TANATAR,  Zeit.  phys.  Chem.,  41,  735  (1902).  • 

86  ROZANOV,  J.  Russian  Phys.  Chem.  Soc.,  48,  168  (1916),  C.  A.,  u,  454. 

87  MARESHKOVSKI,  Ibid.,  45,  2072  (1914),  C.  A..  9,  799. 


194  CATALYSIS  IN  ORGANIC  CHEMISTRY  74 

194.  Cyclizations  and  Transformations  of  Ring  Compounds. 

Hydrobenzamide  when  boiled  with  potash  changes  to  amarine:  38 


C6HB  .  CH  :  N\  C6H5  .  C  . 

)CH.C6H5->  ||  )CH.C6H5. 

C6H6.CH:N/  C6H5.C.NH/ 

195.  The  acetylenic  pinacones  when  kept  on  the  water  bath  with  a 
4%  water  solution  of  mercuric  sulphate,  are  rapidly  and  completely 
isomerized    into    ketohydrofurfuranes.    Doubtless   there    is    at    first 
addition  of  water  to  the  triple  bond  and  then  dehydration  of  the  glycol 
thus  obtained:  39 

CO  -  CH2 
CH3\  yCH3  |         | 

)C(OH)-CiC.C(OH)(  ->     (CH3)2:C        C:(CH3)2 

CH3/  \CH3  \0/ 

196.  In  contact  with  maleic  acid  or  with  other  acids,  dimethyl- 
ketazine  isomerizes  into  trimethyl-pyrazoline:  40 

CH3\  /CH8  CH3.CH-CH2\      /CH3 

)C:N.N:C(  ->  ||  )C( 

CH3/  \CH2  N  —  NH/  \CH3 

197.  Cy  do  -heptane,  heated  to  210°  with  reduced  nickel  in  an 
atmosphere  of  hydrogen,   is  transformed  into   methyl-cyclo-hexane, 
and  likewise  cyclo-octane  gives  dimethyl-cyclo-hexane41 

198.  Sulphuric   acid   provokes    many    isomerizations    among   the 
terpenes.    Thus  pinene,  warmed  with  sulphuric  acid  diluted  with  its 
own  volume  of  water,  is  changed  to  a  mixture  of  terpinolene,  terpinene, 
and  dipentene.42 

LPinene  dissolved  in  glacial  acetic  acid  and  warmed  to  60-70°, 
isomerizes  into  l.limonene  with  evolution  of  heat,  when  5%  of  phos- 
phoric acid  is  added.43  Likewise  phellandrene,  on  contact  with  sul- 
phuric acid,  yields  terpinene44 

Thujone  is  isomerized  to  isothujone  when  it  is  warmed  for  nine 
hours  with  sulphuric  acid  diluted  with  two  volumes  of  water.45 

In  the  presence  of  sulphuric  acid,  pseudo-ionone  passes  into  the 
cyclic  QJ-  and  p-ionones.  Thus  a-ionone  (artificial  extract  of 

38  FOWNES,  Anndlen,  54,  364  (1845). 

39  DUPONT,  Compt.  rend.,  152,  1486  (1911)  and  153,  275  (1911). 

40  CURTIUS  and  FOERSTERLING,  /.  prakt.  Chem.    (2),  51,  394  (1895). 

41  WILLSTATTER  and  KAMETAKA,  Berichte,  41,  1480  (1908). 

42  ARMSTRONG  and  TILDEN,  Berichte,  12,  1754  (1879). 

43  PRINS,  Chem.  WeekbL,  13,  1264  (1916),  C.  A.,  n,  586. 

44  WALLACH,  Anncden,  239,  35   (1887). 

45  WALLACE,  Annalen,  286,  101   (1877). 


75  CONDENSATIONS  BY  ADDITIONS  201 

violets)  is  prepared  by  heating  for  16  hours,  20  parts  pseudo-ionone 
dissolved  in  100  parts  of  water  and  100  parts  of  glycerine  with  2.5 
parts  sulphuric  acid.  Concentrated  sulphuric  acid  gives  mainly 
^3-ionone.  Phosphoric  acid  also  may  be  employed.48 

199.  Migration   of   Atoms.     Migrations   of   halogen   atoms   are 
frequently   effected   by   anhydrous   aluminum   chloride   or   bromide. 
Thus  propyl  bromide,  CH3 .  CH2 .  CH2Br,  boiled  5  minutes  with  10% 
of  aluminum  bromide  is  completely  transformed  into  isopropyl  bro- 
mide, CH3 .  CHBr  .  CH3;  while  4%  of  the  salt  will  effect  the  change  in 
24  hours  in  the  cold.47    The  mechanism  is  apparently  a  separation 
into  propylene  and  hydrobromic  acid  and  a  recombination  of  these  to 
form  isopropyl  bromide. 

Propyl  chloride  is  affected  in  the  same  way.48 

In  the  presence  of  anhydrous  aluminum  chloride  at  110°,  acetylene 
tetrachloride,  CHC12 .  CHC12,  changes  partly  into  the  unsymmetrical 
tetrachlorethane,  CC13 .  CH2C1. 49 

By  warming  with  15  to  20%  of  aluminum  chloride,  a-bromnaph- 
thalene,  dissolved  in  3  or  4  parts  of  carbon  disulphide,  is  transformed 
into  ^-bromnaphthalene.50 

200.  Mercuric  chloride  and  zinc  bromide  greatly  accelerate  the 
isomerization  of  isobutyl  bromide,  (CH3)2CH  .  CH2Br,  into  tertiary- 
butyl  bromide,  (CH3)3CBr. 51 

R\ 

Ethylene  oxides  of  the  type,        )C CH2,  kept  in  contact  with 

R'/\0/ 

R\ 

zinc  chloride,  are  isomerized  into  aldehydes,         /CH  .  CHO.    Thus 

R'/ 

ethylene  oxide  gives  acetaldehyde.62  The  same  transformation  is 
accomplished  by  anhydrous  alumina  acting  on  the  vapor  of  ethylene 
oxide  at  200°. 53 

201.  Concentrated  or  dilute  mineral  acids  frequently  cause  the 
migration  of  atoms  in  a  straight  chain  of  cyclic  hydrocarbon  or  in  a 
ring  containing  nitrogen. 

46  TIEMANN  and  KRUGER,  Berichte,  26,  2693  (1893)  and  31,  808  (1898). 

47  KEKULE    and  SCHROTTER,  Berichte,  12,  2279  (1879).    GUSTAVSON,  J.  Rus- 
sian Phys.  Chem.  Soc.,  15,  61  (1883). 

48  MOUNEYRAT,  Bull.  Soc.  Chim.  (3),  21,  616  (1899). 
4*>  MOUNEYRAT,  Ibid.  (3),  19,  499  (1898). 

e°  Roux,  Ann.  Chim.  Phys.  (6),  12,  344  (1887). 

61  MICHAEL,  SCHARF,  and  VOIGT,  J.  Am.  Chem.  Soc.,  38,  653  (1916). 

52  KASCHIRSKI,  J.  Russian  Phys.  Chem.  Soc.,  13,  76  (1881),  C.,  z88x,  278. 
KRASSUSKI,  Ibid.,  34,  543  (1902),  C.,  1902,  (2),  1095. 

53  IPATIEP  and  LEONTOWITCH,  Beritche,  36,  2016  (1903). 


202  CATALYSIS  IN  ORGANIC  CHEMISTRY  76 

The  1,2  dihydrotetrazines  isomerize  into  the  1,4,  when  heated  with 
alcoholic  hydrochloric  acid,64  thus: 


/NH— 

/C.C6H6  ->   C6H8.C/ 
\NH—  N^CH  \N  - 


202.  Acetylchloraminobenzene,    CH3  .  CO  .  NCI  .  C6H5,    is    trans- 
formed into  p.chloracetanilide,  CH3  .  CO  .  NH  .  C6H4C1,  under  the  in- 
fluence  of  hydrochloric   acid.55    The   same   acid   changes   hydrazo- 
benzene  into  benzidene.56 

C6H5—  NH  C6H4—  NH2 

C6H5—  NH  C6H4—  NH2 

203.  Acids  with  a  double  bond  in  £7  position,  and  hydroxyl  in  the 
a,  are  changed  by  boiling  with  dilute  hydrochloric  acid  into7-keto 
acids.       Thus     phenyl-ot-hydroxycrotonic     acid,     C6H5  .  CH  :  CH  .- 
CH(OH).COOH,  is  changed  into  benzoyl-propionic  acid,  C6H5  .- 
CO  .  CH2  .  CH2  .  COOH.    The  mechanism  of  this  reaction  has  been 
variously  explained.57 

204.  The  aldoximes,  R  .  CH  :  NOH,  of  the  aliphatic  series  are 
changed  to  amides,  R  .  CO  .  NH2,  by  warming  with  sulphuric  acid. 
To  explain  this  change  it  is  sufficient  to  assume  that  there  is  first  a 
dehydration  of  the  oxime  to  the  nitrile  which  is  hydrated  by  the  min- 
eral acid  in  the  usual  way  to  the  amide. 

205.  In  contact  with  sulphuric  acid,  oximes  of  cyclic  ketones  are 
transformed  into  internal  amides,  or  iso-oximes.    Thus  the  oxime  of 
cyclohexanone  yields  the  lactam  of  c-aminocaproic  acid: 

/CH2  .  CH2\  /CH2  .  CH2  .  NH 

CH2(  )C:NOH      ->      CH2(  | 

\CH2  .  CH2/  \CH2  .  CH2  .  CO 

The  concentrated  acid,  to  which  a  little  water  or  acetic  acid  has 
been  added,  is  suitable  for  this  reaction.58 

206.  Alkaline  solutions  also  can  cause  the  migration  of  atoms. 
The  potassium  salt  of  diazobenzene  heated  to  130°  with  concentrated 
caustic  potash  is  changed  to  the  potassium  salt  of  phenylnitrosamine.69 

54  STOLID,  J.  prakt.  Chem.  (2),  73,  299  (1906). 

85  AGREE  and  JOHNSON,  Am.  Chem.  Jour.,  37,  410  (1907). 

56  ZININ,  Annalen,  137,  376  (1865). 

87  FITTIG,  Annalen,  299,  20  (1898).    THIBLB  and  SULZBERGER,  Ibid.,  319,  199 
(1901).    ERLENMEYER,  JR.,  Ibid.,  333,  205  (1904),    BOUGAULT,  Ann.  Chim.  Phys. 
(8),  15,  513  and  Compt.  rend.,  157,  403  (1913). 

88  WALLACH,  Annalen,  312,  171  (1900). 

89  SCHRAUBE  and  SCHMIDT,  Berichte,  27,  522  (18Q4), 


77  CONDENSATIONS  BY  ADDITIONS  210 

/NO 
C6H5.N:N.OK  ->  C6H5.N^      . 

207.  Thiourea,  CS(NH2)2,  on  contact  with  a  solution  of  ethyl 
nitrite,  isomerizes  into  ammonium  isosulphocyanate,  CSN .  NH4.60 

208.  In  certain  cases,  finely  divided  metals,  copper,  nickel,  etc., 
can  bring  about  a  migration  of  atoms,  thus  causing  a  change  of  func- 
tion.   Thus  unsaiurated  alcohols  are  transformed  into  aldehydes  or 
ketones  in  a  way  that  is  easy  to  explain. 

Allyl  alcohol,  CH2  :  CH  .  CH2OH,  passed  in  the  vapor  form  over 
reduced  copper  at  180-300°,  is  changed  almost  entirely  into  propionic 
aldehyde,  CH3 .  CH2CHO,  with  only  slight  traces  of  acroleme, 
CH2  :  CH .  CHO.  The  hydrogen  produced  by  the  decomposition  of 
the  alcohol  by  the  copper  is  immediately  added  to  the  double  bond  of 
the  acroleine.61 

Likewise  a-unsaturated  secondary  alcohols,  R  .  CH  :  CH  .- 
CH(OH)  .R',  mixed  with  hydrogen  over  reduced  nickel  at  195-200°, 
are  isomerized  into  the  ketones,  R  .  CH2 .  CH2 .  CO  .  R'. 62 

§  2.     POLYMERIZATIONS 

209.  Frequently  several  molecules  of  the  same  kind,  having  one 
or  more  double  bonds,  condense  to  a  single  molecule,  which  is  called 
a  polymer  of  the  original  molecule.    The  presence  of  a  catalyst  fre- 
quently causes  such  a  change  or  accelerates  its  velocity.    We  will 
examine  from  this  point  of  view: 

Hydrocarbons. 
Aldehydes. 
Nitriles  and  amides. 

Hydrocarbons 

210.  Ethylene   Hydrocarbons.     Hydrocarbons   of   the   ethylene 
series,  CnH2n,  frequently  change  into  polymers  of  double,  triple,  or 
even  quadruple,  the  original  molecule  yet  retaining  the  same  character 
as  the  original. 

Sulphuric  acid,  either  concentrated  or  slightly  diluted,  frequently 
causes  this  polymerization.  In  fact,  its  action  is  complex  as,  besides 
polymerization,  it  can  cause  the  addition  of  water  to  form  secondary 
or  tertiary  alcohols  and  also  the  formation  of  acid  or  neutral  esters 

60  GLAUS,  Annalen,  179,  129  (1875). 

61  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  463  (1905). 

62  DOURIS,  Compt.  rend.,  157,  55  (1913). 


211  CATALYSIS  IN  ORGANIC  CHEMISTRY  78 

of  sulphuric  acid.  With  hydrocarbons  of  moderate  molecular  weight, 
there  is  principally  the  formation  of  alcohols  and  esters.63  Thus 
sulphuric  acid  diluted  with  its  own  volume  of  water  transforms  tri- 
methyl-ethylene,  (CH3)2C  :  CH  .  CH3,  at  0°,  chiefly  into  dimethyl- 
ethyl-carbinol,  (CH3)  2C  (OH)  .  CH2 .  CH3. 64 

With  ethylene  hydrocarbons  of  high  molecular  weight,  there  is 
chiefly  production  of  polymers,  particularly  dimers.  Thus  duodecene 
is  changed  by  sulphuric  acid  quantitatively  into  viscous  tetracosene 
which  is  stable  in  presence  of  sulphuric  acid.65 

The  concentration  of  the  acid  determines  the  nature  of  the  re- 
action. Thus  a-hexene  and  7-heptene,  with  85%  acid  yield  alkyl 
sulphuric  acids,  while  they  polymerize  in  contact  with  the  normal 
acid,  H2S04. 

The  acid,  diluted  with  20%  of  its  volume  of  water,  changes 
isobutene,  in  the  cold,  to  tributene,  boiling  at  177°. 66 

Trimethyl-ethylene  in  contact  with  sulphuric  acid  diluted  with 
half  its  volume  of  water,  furnishes,  at  0°,  much  diamylene,  boiling 
at  154°. 67 

211.  Zinc  chloride  can  polymerize  unsaturated  hydrocarbons,  e.  g. 
trimethyl-ethylene  into  diamylene,  triamylene,  and  tetra-amylene.68 

Boron  trifluoride  transforms  amylene  into  diamylene.69 

The  use  of  catalysts  under  high  pressures  greatly  favors  the  poly- 
merization of  ethylene  into  unsaturated  hydrocarbons  at  high  tem- 
peratures. The  products  obtained  with  anhydrous  alumina,  under 
70  atmospheres  above  250°,  are  the  same  as  those  produced  by  heat 
alone  in  the  absence  of  the  catalyst.70 

Ethylene  with  anhydrous  zinc  chloride  at  275°  and  70  atmospheres, 
gives  a  gas  containing  36%  ethylene,  3%  hydrogen,  and  61%  satu- 
rated hydrocarbons  and  a  complex  liquid  of  which  85%  is  pentane 
and  hexane  without  any  methyl-cyclobutane.  The  remainder  consists 
of  numerous  hydrocarbons  including  unsaturated  hydrocarbons  boil- 
ing above  145°  and  naphthenes  which  are  particularly  abundant 
around  250°. 

Anhydrous  aluminum  chloride  produces  little  effect  with  ethylene 
at  70  atmospheres  and  240°,  but  at  280°,  a  gas  is  obtained  containing 

63  BROOKS  and  HUMPHREY,  J.  Am.  Chem.  Soc.,  40,  822   (1918). 

64  WISCHNEGRADSKY,  Annolen,  190,  336  (1877). 

65  BROOKS  and  HUMPHREY,  Loc.  cit. 

66  BUTLEROW,  Berichte,  6,  561  (1873). 

67  SCHNEIDER,  Annalen,  157,  207  (1871). 

68  BAUER,  Jahresh.,  1861,  660. 

69  LANDOLPH,  Berichte,  12,  1578  (1879). 

70  IPAHEF,  J.  Russian  Phys.  Chem.  Soc.,  43,  1420  (1911),  C.  A.,  6,  736. 


79  CONDENSATIONS  BY  ADDITIONS  214 

only  saturated  hydrocarbons,  and  no  liquid,  but,  instead,  a  rather 
abundant  carbonaceous  residue.71 

212.  Doubly    Unsaturated    Hydrocarbons.    Acetylene    is    ad- 
sorbed more  energetically  than  hydrogen  by  colloidal  palladium  and 
is  to  a  great  extent  polymerized.72 

Allylene  is  absorbed  by  concentrated  sulphuric  acid  and  is  poly- 
merized into  mesitylene: 73 

3  CH3.C  :CH  =  C6H3(CH3)3(1.3.5). 

This  can  be  explained  by  assuming  that  the  acid  first  causes  the 
hydration  of  the  allylene  to  acetone  (308)  and  then  dehydrates  3 
molecules  of  this  according  to  a  well-known  reaction. 

Similarly  crotonylene,  or  butine(2),  shaken  with  slightly  diluted 
sulphuric  acid  (1  part  water  to  3  parts  acid),  gives  hexamethyl-ben- 
zene.7* 

Valerylene,  C5H8,  shaken  with  sulphuric  acid  changes  into  poly- 
mers, trivalerylene  and  polyvalerylenes.75 

213.  Divinyl,  or  butadiene,  CH2  :  CH  .  CH  :  CH2,  as  well  as  its 
higher    homologs,    piperylene,    CH3 .  CH  :  CH  .  CH  :  CH2,    isoprene, 
CH2  :  C(CH3)  .  CH  :  CH2,       and       dipropylene,     CH2  :  C(CH3)  .- 
C(CH3)  :  CH2,  polymerize  spontaneously  under  the  influence  of  heat 
alone  giving  rise  to  various  elastic  solid  hydrocarbons  resembling 
natural  rubber  and  constituting  the  synthetic  rubbers.    This  poly- 
merization is  greatly  accelerated  by  the  presence  of  various  catalysts. 
Thus  with  5%  metallic  sodium  or  potassium,  the  reaction  which  goes 
on  in  the  cold  or  with  slight  warming,  is  complete  and  is  not  hindered 
by  the  presence  of  non-polymerizable  hydrocarbons.78 

214.  The  polymerization  of  isoprene  by  barium  peroxide  or  ben- 
zoyl  peroxide  or  potassium  sulphide  gives  rise  to  the  intermediate 
formation  of  /3-myrcene, 

CH2  :  CH  .  C  :  CH  .  CH2 .  CH2 .  C  :  CH2, 

CH3  CH3 

a  hydrocarbon  boiling  at  63°  at  20  mm.,  which,  in  turn,  warmed  with 
sodium  or  with  barium  peroxide  changes  quantitatively  into  normal 

71  IPATIEF  and  RUTALA,  Berichte,  46,  1748  (1913). 

72  PAAL  and  HOHENEGGER,  Berichte,  43,  2684  (1910). 

73  SCHROHE,  Berichte,  8,  17  (1875). 

74  ALMEDINGEN,  J.  Russian  Phys.  Chem.  Soc.,  13,  392  (1881),  C.,  1881,  629. 

75  BOUCHARDAT,  Bull  Soc.  Chim.  (2),  33,  24  (1880).    REBOUL,  Annalen,  143, 
373  (1867). 

76  MATTHEWS  and  STRANGE,  English  Pat.,  24,790  (1910).    HARRIES,  Annalen, 
383,  157   (1911). 


215  CATALYSIS  IN  ORGANIC  CHEMISTRY  80 

caoutchouc;  the  direct  polymerization  furnishes  only  an  abnormal 
caoutchouc77 

215.  Glacial  acetic  acid  and  especially  acetanhydride  acting  at 
150°   have  been  recommended   for  the  polymerization  into   caout- 
chouc,78 the  presence  of  0.2%  of  sulphur  or  of  0.002%  of  sulphuric 
acid  in  the  hydrocarbon  being  favorable  to  the  reaction.79 

Trioxymethylene,  at  a  high  temperature  in  an  autoclave,  has  also 
been  proposed  as  a  catalyst  in  this  reaction.80 

216.  Cyclic   Hydrocarbons.    Pinene   heated   twelve  hours   with 
formic  acid  changes  to  a  hydrocarbon  of  double  the  molecular  weight, 

^20-"-32' 

Pinene  is  transformed  into  colophene,  C20H32,  by  contact  with  con- 
centrated sulphuric  acid,  boron  fluoride,  or  phosphoric  anhydride.82 

Pinene  heated  to  50°  with  20%  of  antimony  chloride  is  changed 
into  tetra-terebenthine,  C40H64. 88  Aluminum,  ferric,  and  zinc  chlo- 
rides cause  the  formation  of  analogous  products.84 

217.  Indene.     Indene  polymerizes  on  contact  with  sulphuric  acid 
into  para-indene,  (C9H8)X,  which  melts  at  120°. 85 

Aldehydes 

218.  The  tendency  to  polymerize  is  very  general  among  aldehydes 
and  small  traces  of  various  materials  are  sufficient  to  cause  the  poly- 
merization to  take  place,  whether  the  molecules  thus  condensed  are 
joined  by  carbon  to  carbon  or  by  means  of  the  oxygen  atoms. 

219.  Aldolization.    The  first  method  of  condensation  is  called 
aldolization;  one  of  the  aldehyde  groups  is  preserved  and  the  other 
is  converted  into  a  secondary  alcohol  group.    The  name  comes  from 
aldol,  the  first  example  to  be  studied. 

Acetaldehyde  kept  for  some  time  in  contact  with  a  small  amount 
of  hydrochloric  acid  or  of  zinc  chloride  solution  condenses  to  give 
aldol,  or  butanalol  (1 .  3) :  86 

CH3 .  CHO  +  CH3 .  CHO  =  CH3.CH(OH)  .CH2.CHO 

aldol 

77  OSTROMUISLENSKII  and  KOSHELEV,  J.  Russian  Phys.  Chem.  Soc.,  47,  1928 
(1915),  C.  A.,  10,  1947.    OSTROMUISLENSKII,  Ibid.,  48,  1071  (1916),  C.  A.,  n,  1768. 

78  CHEM.  FABR.  AUF.  ACTIEN,  French  Patent,  433,825 

79  BADISCHE,  French  Patent,  434,587. 

80  GROSS,  French  Patent,  459,987. 

81  LAFONT,  Ann.  Chim.  Phys.  (6),  15,  179  (1888). 

82  SAINTE-CLAIRE-DEVILLE,  Ibid.  (2),  75,  66  (1839)  and  (3),  26,  85  (1849). 

83  PRINS,  Chem.  Weekbl,  13,  1264  (1916),  C.  A.,  n,  586. 
8*  RIBAN,  Ann.  Chim.  Phys.  (5),  6,  42  (1875). 

85  KRAMER  and  SPILKER,  Berichte,  23,  3278  (1890). 

«6  WURTZ,  Compt.  rend.,  74,  1361   (1872!)  and  76,  1165  (1873). 


81  CONDENSATIONS  BY  ADDITIONS  222 

The  same  result  is  obtained  more  readily  by  leaving  acetaldehyde 
for  18  hours  in  contact  with  a  solution  of  neutral  potassium  carbonate 
or  with  a  fragment  of  solid  caustic  potash.87  Also  in  the  presence  of 
zinc  turnings  at  100°,  acetaldehyde  gives  aldol  and  likewise  crotonic 
aldehyde  by  loss  of  water  (795) . 

220.  Likewise  benzaldehyde  heated  with  an  alcoholic  solution  of 
potassium  cyanide  (10%  of  the  weight  of  the  aldehyde),  is  rapidly 
transformed     into     benzolne,     C6H5 .  CH  (OH)  .  CO  .  C6H5. 88       The 
original  aldehyde  group  is  in  this  case  changed  to  a  ketone. 

Anisaldehyde,  CH30  .  C6H4 .  CHO,  with  the  same  reagent,  gives 
aniso'ine,  CH3 .  0  .  C6H4 .  CH  (OH)  .  CO  .  C6H4 .  0  .  CH3. 89 

On  heating  an  hour  and  a  half,  the  same  catalyst  transforms 
cuminaldehyde  into  cuminoine90  and  in  half  an  hour,  furfural  into 
furfuro'ine9* 

221.  The  aldolization  of  several  molecules  of  aldehyde  can  be 
realized  successively  or  simultaneously. 

Under  the  influence  of  milk  of  lime,  formaldehyde  condenses  to 
a  hexose,  CH2(OH)  .  CH(OH)  .  CH(OH)  .  CH(OH)  .  CO  .  CH2OH, 
which  is  racemic  laevulose92  Analogous  condensations  giving  in- 
active arabinose  and  laevulose,  are  realized  in  contact  with  granulated 
tin93  or  with  a  mixture  of  magnesia,  magnesium  sulphate,  and  granu- 
lated lead94  A  similar  condensation  can  be  obtained  starting  with 
trioxymethylene,  (HCOH)8.95 

222.  Second  Method.    The  second  method  in  which  aldehydes 
polymerize  suppresses  the  aldehyde  function,  producing  bodies  called 
paraldehydes  and  metaldehydes,  the  vaporization  of  which  tends  to 
reproduce  the  original  aldehyde. 

Acetaldehyde  in  contact  with  small  quantities  of  sulphur  dioxide, 
anhydrous  zinc  chloride,  hydrogen  chloride,  or  carbonyl  chloride  soon 
warms  up  and  is  converted  into  par  aldehyde,  boiling  at  124°.  The 
same  result  is  obtained  by  warming  it  with  ethyl  iodide  or  by  leaving 
a  solution  of  cyanogen  in  acetaldehyde  to  stand  for  several  days.96 

87  MICHAEL  and  KOPP,  Am.  Chem.  Jour.,  5,  190  (1883). 

88  WOHLER  and  LIEBIG,  Annalen,  3,  276  (1832).    ZININ,  Ibid.,  34,  186  (1840). 
BREUES  and  ZINCKE,  Ibid.,  198,  151  (1879). 

89  ROSSEL,  Ibid.,  151,  33  (1869). 

»o  BOSLER,  Berichte,  14,  324  (1881). 

91  E.  FISCHER,  Annalen,  211,  218  (1882). 

92  LOEW,  Berichte,  22,  475  (1889).    E.  FISCHER  and  PASSMORB,  Ibid.,  22,  359 
(1889). 

oa  LOEW,  J,  prakt.  Chem.  (2),  34,  51  (1886). 

94  LOEW,  Loc.  cit. 

95  SEYEWETZ  and  GIBELLO,  Compt.  rend.,  138,  150  (1904). 

96  LIEBEN,  Annalen,  Supl  Band,  i,  114  (1861). 


223  CATALYSIS  IN  ORGANIC  CHEMISTRY  82 

A  few  bubbles  of  hydrogen  chloride  or  sulphur  dioxide  passed  into 
acetaldehyde  cooled  below  0°,  convert  it  into  metaldehyde,  a  sublim- 
able  solid.97  By  adding  one  drop  of  concentrated  sulphuric  acid  to 
100  cc.  acetaldehyde,  paraldehyde  is  obtained. 

223.  Likewise  by  passing  a  few  bubbles  of  hydrogen  chloride  into 
propionic  aldehyde  cooled  below  0°,  crystals  of  metapropanal  (melt- 
ing at  180°)  are  obtained  along  with  parapropanal,  a  liquid  boiling 
at  169°.    By  a  current  of  hydrogen  chloride  at  — 20°,  metapropanal 
is  formed.98 

When  a  current  of  dry  hydrogen  chloride  is  passed  into  butanal  at 
— 20°,  heat  is  evolved  and,  on  stopping  the  gas,  crystals  of  meta- 
butanal  (melting  at  173°)  separate  out  along  with  oily  parabutanal. 

Under  the  same  conditions,  cenanthal  (hept aldehyde)  gives  para- 
heptaldehyde  (melting  at  20°)  and  metaheptaldehyde  (melting  at 
140°)." 

224.  Isobutyric  aldehyde,  with  a  concentrated  solution  of  sodium 
acetate  at  150°,  is  changed  into  the  dialdehyde  boiling  at  1360.100 
With  a  little  chlorine,  bromine,  iodine,  hydrochloric  acid,  phosphorus 
pentachloride  or  zinc  chloride,  meta-isobutanal,  melting  at  59 °,101  is 
produced. 

With  alcoholic  potash  it  gives  in  succession,  tri-isobutanal 
(b.!54°),  tetra-isobutanal  (b.!90°),  penta-isobutanal  (b.223°),  hexa- 
isobutanal  (b.250°),  and  finally  oily  hepta-isobutanal.™2 

Chloral  behaves  similarly  in  contact  with  various  substances, 
forming  solid  insoluble  metachloral  with  sulphur  dioxide.  Trimethyl 
amine  produces  the  same  effect  rapidly ; 103  fuming  sulphuric  acid 
causes  the  same  polymerization,104  while  pyridine  gives  metachloral 
in  a  gelatinous  form.105 

225.  Third   Method.    Aromatic   aldehydes,   e.   g.   benzaldehyde, 
when  warmed  with  alkali,  undergo  a  special  change,  yielding  the  al- 
cohol and  acid  at  the  same  time: 

2C6H5  -  CHO  +  KOH  =  C6H5  •  CO2K  +  C6H5  •  CH2OH  - 

97  KEKULE  and  ZINCKE,  Ibid.,  162,  125  (1872). 

98  ORNDORF,  Amer.  Chem.  J.,  12,  353  (1890). 

99  FRANKE  and  WOZELKA,  Monatsh.,  33,  349  (1912). 

100  FOSSEK,  Ibid.f  2,  622  (1881). 

101  BARBAGLIA,  Berichte,  5,  1052  (1872)  and  6,  1064  (1873).    DEMTSCHENKO, 
Ibid.,  6,  1176  (1873). 

102  PERKIN,  J.  Chem.  Soc.,  43,  91  (1883). 

103  MEYER  and  DULK,  Annalen,  171,  76  (1874). 

104  BOESEKEN,  Rec.  Trav.  Chim.  Pays-Bos,  29,  104  (1910). 

105  BOBSEKEN  and  SCHIMMEL,  Ibid.,  32,  112  (1913). 


83  CONDENSATIONS  BY  ADDITIONS  228 

Formaldehyde  gives  the  same  reaction  to  some  extent  with  dilute 
caustic  soda.106  On  the  contrary,  acetaldehyde,  with  caustic  soda  or 
potash,  polymerizes  into  a  complex  resin. 

226.  Isobutyric  aldehyde  with  baryta  water  reacts  somewhat  like 
aromatic  aldehydes,  yielding  isobutyl  isobutyrate: 

(CH3)2CH  •  CHO  +  CHO  •  CH(CH3)2  =  (CH3)2CH  -  CO  •  OCH2  -  CH(CH3)2  • 

When  the  solution  is  warmed,  the  ester  is  saponified  into  isobutyl  al- 
cohol and  isobutyric  acid.107 

227.  This  reaction  takes  place  with   all  aliphatic  aldehydes   in 
which   the    carbon   atom   next   to   the   aldehyde    group    carries   no 
hydrogen. 

It  is  sometimes  caused  by  the  presence  of  ethyl  magnesium  iodide. 
With  2,2-dimethyl-propanolal  the  hydroxypivalic  ester  of  2,2-cft- 
methyl-propandiol  is  obtained:  108 


CH3/  \CHO       HOH2C/  \CH3" 

CH3\      /CH2OH  /CH2OH 

c  c 

CH3/    \CH2.0-CO/  \CH,), 

228.  The  same  reaction  can  be  brought  about  with  the  lower 
aliphatic  aldehydes  by  the  use  of  aluminum  ethylate,  A1(OC2H5)3 
(299).  Thus  formaldehyde  is  condensed  into  methyl  formate,  ace- 
taldehyde into  ethyl  acetate,  propionic  aldehyde  into  propyl  propio- 
nate,  even  chloral  into  trichlorethyl  trichloracetate.109 

In  the  case  of  acetaldehyde  this  reaction  goes  quantitatively  in 
24  hours  if  4%  of  ethyl  aluminate  be  used  and  the  mixture  kept  below 
15°.  The  ethylate  can  be  used  in  solution  in  ethyl  acetate,  xylene,110 
or  solvent  naphtha.111 

The  reaction  is  carried  out  in  this  way:  To  135  parts  of  acetalde- 
hyde, 6  parts  of  aluminum  ethylate  containing  10%  aluminum  chlo- 
ride are  added  little  by  little  and  the  mixture  let  stand  for  ten  hours. 
The  yield  is  123  parts  ethyl  acetate.112 

*>«  H.  &  A.  EULER,  Berichte,  38,  2556  (1905). 
107  FRANKE,  Monatsh.  Chem.,  21,  1122  (1900). 
10»  FRANKE  and  KOHN,  Ibid.,  25,  865  (1904). 

109  TISCHENKO,  J.  Russian  Phys.  Chem.  Soc.,  33,  260  (1901). 

110  KONSORTIUM  F.  EbEKTROCH.  IND.,  English  pat.,  26325  and  26,826  of  1913. 
J.  S.  C.  I.,  33,  666  (1914).    German  pat.,  277,188  (1913);  IMRAY,  English  pat., 
1,288  of  1915,  J.  S.  C.  I.,  35,  141  (1916). 

111  German  pat.,  308,043  (1918),  Chem.  Centr.,  1918    (2),  613. 

112  KONSORTIUM  F.  ELEKTROCH.  IND.,  French  patent,  465,965.    J.  Soc.  Chem. 
Ind.,  33,  666  (1914). 


CATALYSIS  IN  ORGANIC^  CHEMISTRY  84 

Ketones 

229.  The  ketones  rarely  polymerize  but  usually  condense  with 
the  loss  of  water. 

However,  aldolization  of  acetone  takes  place  in  the  cold  with  a 
concentrated  solution  of  caustic  soda.113    Thus: 

/CH3  /CH^ 

CH3  •  CO  •  CH3  +  C0(        -  CH3  •  CO  •  CH2  •  C(OH)( 

\CH8  \CH3 

When  the  product  is  heated  with  the  same  alkali,  the  reaction  is 
reversed. 

Nitriles  and  Amides 

230.  Hydrocyanic  acid,  or  formic  nitrile,  HCN,  kept  with  caustic 
potash  or  an  alkaline  carbonate,  desposits  crystals  of  the  empirical 
formula   (CNH)S  which  are  soluble  in  ether  and  appear  to  be  the 
nitrile  of  amino-malonic  acid,  CN  .  CH(NH2)  .  CN,  along  with  brown 
amorphous  material.114    The  same  substance  is  obtained  when  a  small 
fragment  of  solid  potassium  cyanide  is  added  to  a  water  solution  of 
hydrocyanic  acid.115 

231.  Propionic  nitrile,  CH3 .  CH2 .  CN,  dissolved  in  its  own  weight 
of  anhydrous  ether  in  contact  with  20%  metallic  sodium  is  converted 
into  dipropionic  nitrile,  melting  at  47°. 116    Under  the  same  conditions, 
acetonitrile,  CH3 .  CN,  is  converted  into  diacetonitrile,  CH3 .  C(NH)  .- 
CH2 .  CN,  melting  at  52°.117 

232.  When  the  same  nitriles,  pure  and  without  the  ether,   are 
heated  with  metallic  sodium  or  potassium  (1  of  metal  to  9  of  nitrile), 
they  are  polymerized  into  their  trimers,  acetonitrile  into  cyanethine, 
(C2NH3)8.11« 

Benzonitrile   polymerizes   on    contact   with    sulphuric    acid   into 
cyaphenine: 119 

/C— Cells 

f  NX    \N 


113  KOELICHEN,  Z.  phys.  Chem.,  33,  129  (1900). 

114  WIPPERMANN,  Berichte,  7,  767  (1874). 

118  LESCOEUR  and  RIGAUT,  Compt.  rend.,  89,  310;  Bull.  Soc.  Chim.  (2),  34, 
473  (1880). 

««  VON  MEYER,  J.  prakt.  Chem.  (2),  38,  337  (1888). 
i"  HOLTZWART,  Ibid.  (2),  39,  230  (1889). 

118  FRANKLAND  and  KOLBE,  Annalen,  65,  269   (1848).    BAYER,  Berichte,  2, 
319  (1869)  and  4,  176  (1871).    VON  MEYER,  J.  prakt.  Chem.  (2),  27,  153  (1883). 

119  HOFMANN,  Berichte,  i,  198  (1868). 


85  CONDENSATIONS  BY  ADDITIONS  236 

233.  Cyanamide,  either  in  the  cold  in  contact  with  concentrated 
caustic  soda  or  potash,  or  in  a  hot  solution  to  which  is  added  a  little 
ammonia,  is  transformed  into  dicyanamide.120 

§  3.     DEPOLYMERIZATIONS 

234.  Depolymerizations  are  far  more  rare  than  polymerizations, 
since  the  polymers  usually  correspond  to  a  much  more  stable  molec- 
ular state.    In  exceptional  cases,  polymers  can  be  decomposed  into 
the  simple  molecules  by  the  action  of  heat  and  this  return  is  greatly 
facilitated  by  the  very  catalysts  that  cause  the  polymerization. 

This  is  the  case  with  paraldehydes  and  metaldehydes.  The  cat- 
alysts which  at  low  temperature  polymerize  the  aldehydes  into  their 
trimers  break  these  up  at  high  temperatures  to  regenerate  the  alde- 
hydes. A  trace  of  concentrated  sulphuric  acid,  hydrochloric  acid, 
calcium  or  zinc  chloride  or  the  like  is  sufficient  to  change  hot  par- 
aldehydes  into  the  monomolecular  aldehydes.121  Likewise  metalde- 
hydes are  transformed  into  the  aldehydes  by  heating  with  dilute  sul- 
phuric acid.122 

Certain  aldols  can  be  decomposed,  by  warming  with  a  trace  of 
potassium  carbonate,  regenerating  the  two  molecules  of  the  original 
aldehyde.  But  with  benzoine  and  analogous  compounds  this  decom- 
position does  not  take  place  simply. 

235.  The  transformation  of  pinene  and  especially  of  dipentene, 
C10H10,  into  isoprene,  C5H8,  which  is  realized  by  the  action  of  an  in- 
candescent platinum  spiral,123  appears  to  be  due  to  the  catalytic  action 
of  the  metal,  for  this  reaction  can  be  caused  by  passing  the  vapors  of 
the  terpene  over  pumice  impregnated  with  platinum  black  in  an  iron 
tube  at  a  very  low  red.124 

§4.     CONDENSATIONS   BETWEEN   DISSIMILAR 
MOLECULES 

Aldehydes  and  Ketones 

236.  Aldehydes  and  ketones  can  add  molecules  of  other  kinds, 
the  reactions  being  comparable  to  aldolizations  and  aided  by  catalysts 
of  the  same  nature. 

120  HAAO,  Annalen,   122,  22    (1862).    BAUMANN,  Berichte,   6,    1373    (1873). 
GRUBE  and  KRUQER,  Zeit.  phys.  Chem.,  86,  65  (1914). 

121  FRANKE  and  KOHN,  Monatsh.  Chem.,  19,  354  (1898). 

122  BURSTYN,  Ibid.,  23,  737  (1902). 

128  HARRIES  and  GOTTLOB,  Annalen,  383,  228  (1911).  STAUDINGER  and  KLEVER, 
Berichte,  44,  2212  (1911). 

124  SCHORGER  and  SAYBE,  J.  Ind.  Eng.  Chem.,  7,  924  (1915). 


237  CATALYSIS  IN  ORGANIC  CHEMISTRY  86 

This  reaction  is  general  between  aldehydes  and  nitroparaffines  and 
gives  nitroalcohols.  The  presence  of  an  alkali,  or  better  an  alkali 
carbonate,  is  sufficient  to  cause  the  reaction. 

By  adding  a  small  fragment  of  potassium  bicarbonate  to  a  mix- 
ture of  equal  molecules  of  nitromethane  and  acetaldehyde,  with  an 
equal  volume  of  water,  l-nitropropanol(2)  is  obtained: 125 

CH3  •  CO  -  H  +  CH3NO2  =  CH3  •  CH(OH)  -  CH2NO2  - 

Likewise  nitroethane  condenses  with  formaldehyde  in  the  presence 
of  a  little  neutral  potassium  carbonate  to  give  2-nitropropyl  alcoholt 
CH3 .  CH(N02)  .  CH2OH.126 

Several  aldehyde  molecules  may  take  part  in  the  reaction.  Nitro- 
propane  and  formaldehyde  with  a  little  potassium  carbonate  give 
2-nitro-methanol(2)-butanol(l) : 127 

CH3-CH2-CH2N02  +  2HCHO  =  CH3-CH2C(N02)(CH2OH)2- 

A  mixture  of  formaldehyde  (commercial  formaldehyde  solution) 
and  nitro-methane  reacts  violently  on  the  addition  of  a  fragment  of 
potassium  bicarbonate  to  give  2-nitro-methylol(2)propanediol(l,3), 
a  nitro-triprimary  alcohol  melting  at  158°. 128 

3HCHO  +  CH3N02  =  C(N02)(CH2OH)3- 

237.  The   mixture    of    glyceric    aldehyde    and    dihydroxy 'acetone 
which  is  produced  by  the  air-oxidation  of  glycerine  in  the  presence  of 
finely  divided  platinum   (92),  condenses  into  i-laevulose  in  contact 
with  a  water  solution  of  caustic  soda: 129 

CH2OH  •  CHOH  •  CHO  -  +  CH2OH  -  CO  •  CH2OH  = 

CH2OH  •  CHOH  -  CHOH  -  CHOH  -  CO  -  CH2OH  - 

238.  Acetone  reacts  with  chloroform  in  the  presence  of  solid  caus- 
tic   potash    to    give    acetone-chloroform    or    trichlor-tertiary -butyl 
alcohol: 

(CH3)2CO  +  HCC13  =  (CH3)2  -  C(OH)  -  CC13  • 

To  a  mixture  of  500  parts  acetone  and  100  parts  chloroform,  300 
parts  of  pulverized  caustic  potash  are  added  very  slowly  and  the  mix- 
ture left  for  36  hours.130 

239.  Anhydrous  aluminum  chloride  can  sometimes  cause  the  same 
"5  HENRY,  Bull  Soc.  Chim.  (3),  13,  993  (1895). 

"6  HENRY,  Ibid.,  15,  1223  (1896). 

127  PAUWELS,  Chem.  CentbL,  1898    (1),  193. 

128  HENRY,  Compt.  rend.,  121,  210  (1895). 

129  E.  FISCHER  and  TAFBL,  Berichte,  22,  106  (1882).    WOHL  and  NEUBERG, 
Ibid.,  33,  3098  (1900). 

130  WILLGERODT  and  GENIESER,  J.  prakt.  Chem.  (2),  37,  361  (1888). 


87  CONDENSATIONS  BY  ADDITIONS  224 

sort  of  reactions    Thus  chloral  gives  an  addition  compound  with 
naphthalene,  C10H7.CH(OH)  .  CC13.131 

240.  Acetylation  of  Aldehydes.    The  addition  of  the  anhydrides 
of  monobasic  organic  acids  to  aldehydes  yields  esters  of  the  ethylidene 
glycols  corresponding  to  the  aldehydes.    This  reaction  is  catalyzed 
by  the  presence  of  various  metal  salts,  copper  sulphate,  zinc  chloridef 
ferric  chloride,  and  stannic  chloride  and  even  by  sulphuric  acid.    Thus 
benzaldehyde  and  acetanhydride  give  benzylidene  acetate  quantita- 
tively in  the  presence  of  copper  sulphate: 

C6H5-CHO  +  (CH3CO)20  =  C6H5-CH(0-COCH3)2- 

In  the  presence  of  stannic  chloride,  vanilline  gives  a  quantitative 
yield  of  the  triacetate,  the  phenol  group  being  simultaneously 
acetylated.132 

Hydrocarbons 

241.  Unsaturated  hydrocarbons,  ethylenic  or  acetylenic,  may  add 
themselves  to  hydrocarbons  in  the  presence  of  aluminum  chloride.133 
By  passing  acetylene   into   benzene   containing   aluminum   chloride, 
symmetrical  diphem/l-ethane  is  obtained:  134 

C6H6  +  CH  :  CH  +  C6H3 


and  also  a  certain  amount  of  styrene  formed  by  the  addition  of  only 
one  molecule  of  benzene: 


C6H6  +  CH  i  CH  =  CeHg-CH:  CH2. 

By  passing  ethylene  into  a  warm  mixture  of  diphenyl  and  alumi- 
num chloride,  ethyl-diphenyl  is  obtained: 

CeHs  •  Cells  -|-  CH2  :  CH2  =  CeHs  •  CeEU  •  CH2  •  CHa 

along  with  some  of  the  diethyl  derivative.135 

242.  In  an  analogous  way  anhydrous  aluminum  chloride  causes 
the  addition  of  carbon  tetrachloride  or  of  chloroform  to  ethylenic 
chlorine  derivatives. 

Thus   trichlor  ethylene,   CC12  :  CHC1,   gives,  with   carbon   tetra- 

131  TRANSPORTER  and  DANIELS,  J.  Amer.  Chem.  Soc.,  37,  2560  (1915). 

132  KNOEVENAGEL,  Annalen,  402,  111   (1913). 

133  This  may  be  considered  as  a  case  of  the  Friedel  and  Crafts  reaction. 
A  trace  of  water  is  always  present  and  reacts  with  the  aluminum  chloride  to 
give  hydrochloric  acid  which  adds  to  the  hydrocarbon  to  form  an  alkyl  chloride 
which  then  reacts  in  the  usual  way  liberating  hydrochloric  acid  which  repeats 
the  reaction.  —  E.  E.  R. 

13*  VARET  and  VIENNE,  Bull.  Soc.  Chim.  (2),  47,  919  (1887). 
135  ADAM,  Bull.  Soc.  Chim.  (2),  47,  689  (1887)  and  Ann.  Chim.  Phys.  (6), 
15,  252  (1888). 


243  CATALYSIS  IN  ORGANIC  CHEMISTRY  88 

chloride,  heptachlorpropane,  CC13 .  CHC1 .  CC18,  boiling  at  249°,  and 
with  chloroform,  hexachlorpropane,  CC13 .  CHC1 .  CHC12,  boiling  at 
216°. 

Likewise  dichlorethylene,  CHC1  :  CHC1,  and  chloroform  give 
symmetrical  pentachlorpropane,  CHC12 .  CHC1 .  CHC12,  boiling  at 
1980.136  See  Chapter  XX  for  the  reverse  reactions  caused  by 
aluminum  chloride. 

243.  Stannic  chloride  causes  an  analogous  addition  of  ethylenic 
or  cyclohexenic  chlorides  to  acid  chlorides  to  form  a-chlorketones. 
Aluminum  chloride  also  can  be  used  as  catalyst  in  the  reaction  but  is 
not  so  good.137 

136  PRINS,  J.  prakt.  Chem.  (2),  89,  414  (1914). 
187  DARZENS,  Compt.  rend.,  150,  707  (1910). 


CHAPTER   V 
OXIDATIONS 

I.     Direct    Oxidations   by    Gaseous    Oxygen 

244.  The  action  of  oxygen  on  various  substances,  or  oxidations, 
can  be  divided  into  three  groups: 

1.  Oxidations  which  take  place   spontaneously   as   soon  as  the 
oxidisable  material  and  oxygen  are  brought  together  under  the  proper 
conditions  of  temperature  and  pressure.1 

2.  Oxidations  which  are  brought  about  by  the  simultaneous  oxida- 
tion of  certain  substances  called  auto-oxidisers. 

3.  Oxidations  effected  by  substances  which  are  apparently  un- 
changed and  which  are  called  oxidation  catalysts. 

At  first  sight  only  the  latter  seem  to  belong  in  the  present  treatise. 
But  even  in  the  first  group,  catalytic  phenomena  are  of  more  or  less 
importance.  We  have  already  mentioned  (73)  the  influence  of 
moisture  on  reactions.  Practically,  the  amounts  of  water  vapor  con- 
tained in  the  air  or  in  the  oxygen,  even  when  they  are  dried  by  the 
usual  means,  are  sufficient  to  facilitate  oxidations  of  the  first  class. 

The  case  of  induced  oxidations,  that  is  as  a  consequence  of  simul- 
taneous oxidations,  has  been  examined  in  Chapter  III  (150),  and  we 
have  shown  how  we  can  sometimes  pass  from  the  mechanism  of  such 
reactions  to  catalytic  oxidations  which  should  be  specially  examined. 

245.  Platinum.    The  direct  formation  of  a  sort  of  unstable  oxide 
on  the  surface  of  the  platinum  (154)  permits  us  to  explain  the  im- 
portant role  of  this  metal  in  many  oxidations.    Its  activity  should 
be  proportional  to  its  surface  and  it  can  be  shown  that  the  surface 
is  immeasurably  larger  for  platinum  sponge  and  especially  for  the 
black  than  it  is  for  the  same  amount  of  metal  in  foil  or  wire. 

246.  The  use  of  platinum  black  enables  us  to  effect  many  oxida- 
tions.   Ethyl  alcohol  poured  on  platinum  black  is  vigorously  oxidised 
to  acetaldehyde  and  acetic  acid;  the  black  is  sometimes  made  incan- 
descent and  the  alcohol  may  take  fire. 

1  In  cases  of  this  kind  it  is  practically  impossible  to  eliminate  the  catalytic 
effect  of  the  interior  surfaces  of  the  walls  of  the  containing  vessel  and  hence  it 
is  sometimes  difficult  to  distinguish  between  reactions  of  this  kind  and  those  of 
Class  3.  — H.  D.  GIBBS. 

89 


247  CATALYSIS  IN  ORGANIC  CHEMISTRY  90 

Formic  and  oxalic  acids  are  burned  to  water  and  carbon  dioxide.2 
Alcohols  are  usually  oxidised  to  aldehydes  and  even  to  acids. 

Cinnamic  aldehyde  can  be  obtained  thus  from  the  corresponding 

alcohol.3 

By  oxidising  glycerine  by  air  in  the  presence  of  platinum  black, 

the  isomers,  gly eerie  aldehyde  and  dihydroxy acetone,  are  obtained:  * 

CH2OH  -  CHOH  •  CH2OH  +  O  =  H2O  +  CH2OH  •  CHOH  •  CHO 
CH2OH  -  CHOH  -  CH2OH  +  O  =  H2O  +  CH2OH  •  CO  •  CH2OH  - 

However,  platinum  black  has  no  effect  on  a  mixture  of  carbon 
monoxide  and  oxygen.5 

247.  The  results  given  by  the  black  are  irregular  because  its  action 
is  too  violent,  particularly  at  the  beginning  of  the  reaction. 

By  substituting  for  it,  platinized  asbestos  where  the  active  ma- 
terial is  diluted  by  a  large  proportion  of  inert  material,  regular  oxida- 
tion of  vapors  mixed  with  suitable  amounts  of  oxygen  or  of  air,  is 
obtained.  The  manufacture  of  sulphur  trioxide  is  only  an  application 
of  this  on  the  large  scale. 

248.  Colloidal  platinum  (67)  has  intense  oxidising  power,  greater 
than  that  of  the  black.     It  gives  50%  carbon  dioxide  with  a  mixture 
of  carbon  monoxide  and  half  its  volume  of  oxygen.5 

249.  Platinum  in  very  fine  wire  or  very  thin  foil  is  employed 
industrially  in  the  oxidation  of  ammonia  gas  by  the  oxygen  of  the 
air.    The  gaseous  mixture,  previously  heated  to  about  300°,  is  passed 
over  the  metal  which  is  thereby  maintained  in  incandescence.6    Con- 
tact with  the  metal  for  one-five-hundredth  of  a  second  is  sufficient 
to  obtain  a  good  yield  of  nitrous  vapors  which  are  easily  transformed 
into  nitric  acid. 

It  furnishes  also  an  excellent  method  for  the  regular  oxidation  of 
alcohols  and  of  other  sufficiently  volatile  organic  substances.7  Trillat 
has  described  a  method  of  operating  which  makes  it  easy  to  attain 
this  end  by  the  aid  of  a  platinum  wire  which  is  heated  by  a  current 
that  can  be  regulated  at  will  for  any  desired  temperature  8  and  over 
which  a  current  of  air  passes  laden  with  the  vapors  of  the  substance 
to  be  oxidised. 

2  MULDER,  Rec.  Trav.  Chim.  Pays-Bos,  2,  44  (1883). 

3  STRECKER,  Annalen,  93,  370  (1855). 

4  GRIMAUX,  Bull.  Soc.  Chim.  (2),  45,  481  (1886). 

5  PAAL,  Berichte,  49  548  (1916). 

6  The  points  that  are  used  in  pyrography  for  burning  designs  on  wood 
contain  leaves  of  platinum  foil  which  are  heated  by  the  catalytic  combustion 
of  the  mixture  of  air  and  combustible  vapors  forced  over  them.  —  E.  E.  R. 

7  Better  catalysts  than  platinum  are  known  for  the   oxidation  of  many 
alcohols.    See  note  to  254  infra.  —  H.  D.  GIBBS. 

s  TRILLAT,  Bull.  Soc.  Chim.  (3),  27,  797  (1902). 


91  OXIDATIONS  251 

Under  these  conditions  methyl  alcohol  is  oxidised  below  200° 
chiefly  to  formaldehyde  with  some  methylal  and  water  but  no  acid. 
The  acid  appears  when  the  spiral  reaches  a  dull  red,  at  the  same  time 
that  the  formaldehyde  and  methylal  increase.  At  a  cherry  red  these 
decrease  and  the  proportion  of  carbon  dioxide  increases  with  increase 
of  incandescence. 

The  presence  of  water  in  the  methyl  alcohol  favors  the  oxidation 
which  goes  best  when  20%  of  water  is  present. 

Ethyl  alcohol  is  oxidised  as  low  as  225°  and  readily  at  a  dull  red 
with  a  yield  of  16.8%  of  acetaldehyde  and  2.3%  acetal.  The  results 
are  less  and  less  favorable  as  the  molecular  weight  of  the  alcohol 
increases. 

With  propyl  alcohol  the  yield  of  aldehyde  is  about  the  same  as 
with  ethyl,  but  is  12%  for  normal  butyl  alcohol  and  5%  for  isobutyl. 
Isopropyl  alcohol  gives  16%  acetone.  Tertiary  butyl  alcohol  breaks 
up,  on  oxidation,  into  formaldehyde,  acetone  and  water. 

Allyl  alcohol  gives  5.8%  acroleine,  some  acrylic  acid,  formaldehyde 
and  glyoxal. 

Glycol  oxidises  at  90°,  raising  the  spiral  to  incandescence  and 
yielding  formaldehyde,  glycolic  aldehyde  and  glyoxal.9  Glycerine 
gives  principally  formaldehyde  and  acroleine. 

Aromatic  alcohols  likewise  produce  some  of  the  corresponding 
aldehyde.  Benzyl  alcohol  has  furnished  4%  benzaldehyde  and 
cuminyl  alcohol,  5.7%  cuminic  aldehyde. 

Cinnamic  alcohol  gives  some  cinnamic  aldehyde  at  a  dull  red  and 
cinnamic  acid  and  benzaldehyde  at  higher  temperatures. 

Isoeugenol  oxidises  at  a  dull  red  to  give  2.9%  vanilline  mixed  with 
the  unchanged  substance.10 

250.  The  use  of  porous  porcelain  impregnated  with  platinum  is 
advantageous  for  securing  the  complete  oxidation  of  organic  com- 
pounds in  combustion  analysis.11 

251.  Metals  of  the  Platinum  Group.     The  various  metals  of  this 
family  may  be  used  as  sponge  or  better  as  black  for  the  same  pur- 
poses. 

Palladium  black  gives  good  results.12 

Osmium,  a  more  moderate  catalyst,  sometimes  has  advantages. 
In  the  oxidation  of  cyclohexene,  it  gives  some  cyclohexenol  accom- 

»  TRILLAT,  Bull.  Soc.  Chim.  (3),  29,  35  (1903). 
™  TRILLAT,  Bull.  Soc.  Chim.  (3),  29.  35  (1903). 

11  CARRASCO  and  BBLLONI,  /.  Pharm.  and  Chim.  (6),  27,  469;  Chem.  Centbl., 
1908    (2),  95. 

12  WIBLAND,  Berichte,  46,  3327  (1913). 


252  CATALYSIS  IN  ORGANIC  CHEMISTRY  92 

panied  by  adipic  acid  and  other  products.    The  other  metals  of  the 
platinum  family  are  not  suitable  for  these  reactions. 

Tellurium  may  be  used,  but  it  is  less  active  than  osmium.13 
Colloidal  irridium  can  catalyze  the  oxidation  of  carbon  monoxide 
as  does  colloidal  platinum,  but  colloidal  osmium  is  less  efficient.1* 

252.  Gold  and  Silver.    Gold  and  silver  can  be  substituted  for 
platinum  in  the  preparation  of  formaldehyde.    Silvered  asbestos  ob- 
tained by  the  reduction  of  the  nitrate  by  formic  acid  and  asbestos 
gilded  by  the  reduction  of  the  chloride  are  more  active  than  platinized 
asbestos  (245)  ,16 

253.  Copper.    In  the  oxidation  of  methyl  alcohol  by  the  method 
of  Trillat  (248),  the  platinum  spiral  can  be  replaced  by  a  roll  of 
copper  gauze  heated  to  a  dull  red. 

The  results  obtained  are  entirely  similar.  In  operating  thus  with 
a  current  of  2.3  to  2.7  liters  of  air  per  minute,  carrying  0.5  to  0.8  g. 
methyl  alcohol,  copper  gauze  gives  a  yield  of  48.5%  formaldehyde 
at  330°.  There  is  at  the  same  time  production  of  carbon  monoxide, 
carbon  dioxide  and  water  vapor.16 

The  direct  oxidation  of  methane  by  air  in  contact  with  copper  or 
silver  is  a  practicable  method  for  preparing  formaldehyde.  A  mix- 
ture of  one  volume  of  moist  air  with  three  volumes  of  methane  is 
passed  over  either  of  these  metals  or  over  a  mixture  of  the  two.  The 
formaldehyde  that  is  produced  is  taken  out  by  contact  with  water 
and  the  residual  gases  are  passed  again  over  the  catalyst.17 

254.  Fokin,  operating  under  identical  conditions  with  air  saturated 
with  methyl  alcohol  vapor  passed  over  various  catalysts,  has  obtained 
the  following  yields  of  formaldehyde  (figured  on  the  methyl  alcohol 
used) : 18 

Gilded  asbestos    71% 

Silvered  asbestos    64-66 

Coppered  asbestos  43-47 

Platinized  asbestos    5.2 

Reduced  cobalt    2.8 

Manganese  in  powder 2 

Aluminum  turnings   1.5 

Reduced  nickel  1.08 

18  WILLSTATTER  and  SONNENFELD,  Berichte,  46,  2952  (1913). 

"  PAAL,  Berichte,  49,  548  (1916). 

16  FOKIN,  J.  Russian  Phys.  Chem.  Soc.,  45,  286  (1913) ;  C.  A.,  7,  2227. 

16  ORLOFF,  /.  Russian  Phys.  Chem.  /Soc.,  39,  855  and  1023  (1907) ;  C.  A.,  2, 
263  and  1692. 

1T  VEREIN  p.  CHEM.  IND.,  German  patent,  286,731,  /.  Soc.  Chem.  Ind.,  35, 
73  (1916). 

18  FOKIN,  J.  Russian  Phys.  Chem.  Soc.,  45,  286  (1913) ;  C.  A.,  7,  2227. 


93  OXIDATIONS  266 

A  maximum  yield  of  84%  was  obtained  by  a  mixture  of  silver  and 
copper.  The  silvered  or  gilded  asbestos  requires  an  initial  tempera- 
ture of  only  200-250°  and  the  heat  evolved  is  sufficient  to  maintain 
it  at  a  suitable  temperature. 

Copper  used  alone  requires  continual  heating,  but  this  can  be 
avoided  by  placing  ahead  of  the  copper  gauze  some  fragments  of 
pumice  impregnated  with  platinum  or  palladium  the  incandescence  of 
which  heats  the  gas  sufficiently.19 

The  presence  of  lead  in  the  copper  is  unfavorable. 

Ethyl,  propyl,  isobutyl  and  isoamyl  alcohols  may  be  oxidised 
under  like  conditions.20  Ether  is  oxidised  to  formaldehyde  and  acet- 
aldehyde.21  Various  hydrocarbons  have  been  submitted  to  regular 
oxidation  by  the  same  process  but  the  products  have  not  been  fully 
studied.22 

255.  As  acetaldehyde  can  be  prepared  from  acetylene  (309),  its 
direct  oxidation  to  acetic  acid  is  an  interesting  industrial  problem. 

It  appears  to  be  realized  by  the  use  of  platinum;  the  aldehyde 
vapors  carried  by  air  or  oxygen  over  platinized  asbestos  kept  at  130- 
40°  are  regularly  transformed  into  acetic  acid.23 

256.  The  same  metals  may  be  used  as  catalysts  for  the  direct 
oxidation  of  ammonia  or  amines. 

Moist  ammonia  yields  ammonium  nitrite  with  a  little  nitrate  and 
very  little  free  nitrogen. 

Moist  methyl  amine  gives  formaldehyde  along  with  ammonium 
nitrite  and  nitrate,  while  ethyl  amine  gives  some  acetaldehyde. 

Dimethylaniline  produces  formaldehyde  and  a  complex  aromatic 
amine.24  Aniline,  toluidine  and  pyridine  are  oxidised  with  the  forma- 
tion of  complex  oily  products.25 

19  The  oxidation  of  isopropyl  alcohol  has  been  extensively  investigated  by 
R.  R.  Williams  and  H.  D.  Gibbs  in  connection  with  the  utilization  of  the  waste 
unsaturated  gases  obtained   in  large   quantities   from  the   petroleum   cracking 
stills.    It  was  found  that  the  best  catalyst  was  brass  (zinc  and  copper).    The 
isopropyl  alcohol  is  mixed  with  air  and  passed  through  brass  gauze  at  about 
200°.    With  a  catalytic  chamber  of  a  proper  volume  in  relation  to  the  radiation 
surface,  the  reaction  is  continuous  and  requires  no  external  heat.    The  yield  of 
acetone  is  over  90%  of  the  theory.    That  the  reaction  is  essentially  a  dehydro- 
genation  is  shown  by  passing  the  isopropyl  alcohol  over  the  catalyst  without 
the  oxygen  of  the  atmosphere,  acetone  is  formed  but  the  necessary  heat  must 
be  supplied  externally.    This  work  was  done  for  the  U.  S.  Government  during 
the  war  but  the  report  has  not  yet  been  published.  —  H.  D.  GIBBS. 

20  ORLOFF,  Ibid.,  40,  203  (1908);  C.  A.,  2,  3346. 

21  ORLOFF,  Ibid.,  p.  799;  C.  A.,  3,  1147. 

22  ORLOFF,  Ibid.,  p.  652. 

23  DREYFUS,  French  patent,  487,412  (1918). 

24  TRILLAT,  Bull.  Soc.  Chim.  (3),  29,  873  (1903). 

28  ORLOFF,  /.  Russian  Phys.  Chem.  Soc.,  40,  659  (1908). 


257  CATALYSIS  IN  ORGANIC  CHEMISTRY  94 

257.  Carbon.    The  less  combustible  forms  of  carbon  may  serve 
as  oxidation  catalysts. 

Coke  at  200°  aids  in  transforming  toluene  into  benzoic  acid.26  27 
Coal  and  lignite  after  being  heated  in  the  air  to  300°  are  good 
oxidation  catalysts  between  150  and  300° ;  the  action,  being  partly  due 
to  the  oxide  of  iron  which  they  contain,  is  increased  by  the  addition 
of  ferric  oxide.  They  can  be  used  in  the  oxidation  of  ethyl  alcohol 
to  acetaldehyde  and  acetic  acid,  and  of  toluene  into  benzaldehyde 
and  benzoic  acid.  Anthracene  gives  anthraquinone  and  borneol  forms 
camphor  and  camphoric  acid.28 

258.  Metallic  Oxides.    A  large  number  of  metallic  oxides  act  as 
oxidation  catalysts  and  for  the  most  of  them  this  property  can  be 
readily  explained  by  the  fact  that  they  are  readily  reduced  to  the 
metals  or  to  lower  oxides  by  the  substances  to  be  oxidised  and  are 
readily  reoxidised  directly  by  oxygen.     This  is  the  case  with  the  oxides 
of  copper,  nickel  and  cobalt.    When  alcohol  vapors  alone  are  passed 
over  copper  oxide  moderately  heated,  aldehyde  is  formed  and  the 
oxide  is  reduced,  but  if  the  air  is  mixed  with  the  alcohol  vapors  the 
copper  is  immediately  reoxidised  and  can  recommence  the  oxidation 
of  the  alcohol.    A  like  explanation  fits  the  case  of  ferric  oxide,  which 
can  be  reduced  to  a  lower  oxide  which  is  reoxidised  by  the  air.    It  is 
more  difficult  to  perceive  the  mechanism  in  the  case  of  oxides  which 
can  not  be  reduced  to  suboxides  e.  g.  chromium  sesquioxide  which  is, 
nevertheless,  an  excellent  oxidation  catalyst.29 

The  catalytic  activity  of  iron  sesquioxide,  such  as  is  obtained  by 
roasting  pyrites,  is  utilized  industrially  in  the  manufacture  of  sul- 
phuric acid  by  the  contact  process. 

259.  The  use  of  metallic  oxides  as  catalysts  in  the  oxidation  of 
organic  compounds  has  until  recent  years  been  limited  to  copper  oxide 

26  DBNNSTEDT  and  HASSLER,  German  patent,  203,848,  Chem.  Centrbl.,  1908, 
(2),  1750. 

27  During  the  war  various   forms  of  carbon  were   extensively   studied  as 
adsorbents  for  gases  and  as  catalysts  for  certain  reactions.    Very  active  forms 
of  charcoal  were  developed  by  high  heat  treatments.    These   charcoals  were 
found  to  be  excellent  clarifying  agents  for  solutions,  and  some  forms  catalyzed 
certain  reactions  to  a  high  degree.    The  reaction  between  chlorine  and  water 
was  found  to  be  quite  rapid  at  low  temperatures,   even   so    low  as  0°,  and  at 
100°  it  is  very  vigorous.    The  reaction  is  2  C12  +  2H2O  — >  4HC1  +  02.    This 
would  constitute  a  reversal  of  the  Deacon  process  were  it  not  for  the  fact  that 
the  oxygen  does  not  appear  as  such  but  unites  with  the  carbon  gradually  con- 
suming the  catalyst.    See:    The  Production  of  Hydrochloric  Acid  from  Chlorine 
and  Water.    GIBBS,  /.  Ind.  and  Eng.  Chem.,  12,  538  (1920).  — H.  D.  GIBBS. 

28  WOOG,  Compt.  rend.,  145,  124  (1907) ;  C.  A.,  i,  2690. 

29  SABATIER  and  MAILHE,  Compt.  rend.,  142,  1394  (1906);  C.,  1906,  (2),  402. 


95  OXIDATIONS 

which  is  the  real  agent  when  copper  is  used,  as  has  been  said  above. 
Sabatier  and  Mailhe  have  shown  that  the  oxides  of  copper,  nickel, 
and  cobalt,  as  well  as  those  of  chromium,  manganese,  uranium,  etc., 
have  catalytic  properties  entirely  comparable  to  those  of  finely 
divided  platinum.  When  these  oxides  are  heated  to  200°  in  a  mix- 
ture of  oxygen  with  the  vapors  of  aliphatic  hydrocarbons  (methane, 
pentane,  hexane,  and  heptane),  they  become  incandescent  and  main- 
tain themselves  so,  giving  mainly  water  and  carbon  dioxide,  but  also 
a  certain  amount  of  aldehyde  and  acid.29 

Almost  simultaneously  with  the  above  work,  Matignon  and 
Trannoy  have  shown  the  possibility  of  realizing  a  lamp  without  flame 
by  the  aid  of  asbestos  fibers  impregnated  with  the  oxides  of  iron, 
nickel,  chromium,  copper,  manganese,  cerium,  and  silver  suspended 
in  a  mixture  of  air  and  ether  vapor.30 

The  use  of  ferric  oxide  between  175  and  300°  permits  the  regular 
oxidation  of  toluene  to  benzaldehyde ;  the  most  favorable  tempera- 
ture is  280°  and  the  yield  of  aldehyde  may  reach  20%.  Above  280° 
the  oxide  becomes  incandescent  and  there  is  partial  charring  of  the 
products. 

Employed  in  the  same  way,  nickel  oxide  gives  benzaldehyde  above 
150°,  while  at  270°  incandescence  begins  to  manifest  itself. 

With  copper  oxide  (oxidised  turnings),  the  reaction  takes  place 
between  180  and  260°. 31 32 

80  MATIGNON  and  TRANNOY,  Compt.  rend.,  142,  1210  (1906);  C.,  1906  (2), 
202. 

31  WOOG,  Compt.  rend.,  145,  124  (1907),  C.  A.,  i,  2690. 

32  The  catalytic  oxidation  of  carbon  monoxide  at  low  temperatures  may  be 
brought  about  by  certain  metals  such  as  platinum  and  palladium  but  the  time 
of  contact  necessary  for  complete  oxidation  is  quite  great.    Mixtures  of  certain 
metallic  oxides  are  much  more  effective  and  may  bring  about  the  catalytic  oxida- 
tion of  carbon  monoxide  at  room  temperatures  with  a  surprisingly  short  time 
of  contact.    These  mixed-oxide  catalysts  require  careful  preparation  in  order 
that  they  may  function  under  these  conditions.    Fineness  of  subdivision  and 
intimacy  of  admixture  of  the  ingredients  are  among  the  most  essential  condi- 
tions.   The  most  important  of  this  class  of  catalysts  for  the  oxidation  of  carbon 
monoxide  contains,  as  its  essential  constituent,  manganese  dioxide  made  by  the 
method  of  Fremy  (Compt.  rend.,  82,  1213  (1876).    Copper  oxide  or  silver  oxide, 
when  properly  incorporated  with   this  manganese   dioxide,  gives   an   excellent 
catalyst  which  is  capable  of  effecting  the  catalytic  oxidation  with  great  rapidity 
even  at  temperatures  somewhat  below  0°  C. 

To  prepare  the  catalyst,  the  Fremy  oxide  is  washed  free  of  sulphates  and 
filtered  on  a  Buchner  funnel.  This  paste,  usually  containing  about  60%  of  water, 
is  analyzed  for  moisture  by  drying  to  constant  weight  at  130°  in  oxygen.  A 
weighed  amount  of  this  paste  is  mixed  with  a  large  volume  of  cold  water,  care 
being  taken  to  secure  a  uniform  suspension.  To  this  suspension  is  added  such 


260  CATALYSIS  IN  ORGANIC  CHEMISTRY  96 

260.  Vanadium  pentoxide  is  also  a  very  active  oxidation  catalyst 
and  can  transform  the  vapors  of  ethyl  alcohol  mixed  with  air  into 
acetaldehyde  and  acetic  acid.33    Acetaldehyde  can  also  be  changed 
to  acetic  acid;  this  oxidation  is  readily  realized  by  passing  a  current 
of  air  through  a  solution  of  the  aldehyde  in  glacial  acetic  acid  con- 
taining oxides  of  vanadium,34  uranium 35  and  iron.36 

261.  Cerium  oxide  also  can  be  employed  for  transforming  ace- 
taldehyde into   acetic   acid    (256).    The  aldehyde  mixed   with    1% 
cerium  oxide  is  submitted  to  the  action  of  oxygen  at  two  atmospheres 
or  of  air  at  higher  pressures.    The  oxidation  evolves  heat  and  gives 
a  yield  of  95%.3T 

an  amount  of  a  solution  of  copper  or  silver  nitrate,  as  the  case  may  be,  as  will 
give  a  mixture  of  75%  of  manganese  dioxide  to  25%  of  the  other  oxide  and, 
with  continual  vigorous  stirring,  a  solution  of  sodium  carbonate  is  run  in  till 
precipitation  is  just  complete.  The  precipitate  is  filtered,  carefully  washed,  and 
thoroughly  dried  at  about  130°.  In  order  to  produce  a  harder  and  less  friable 
product,  it  is  well  to  compress  the  material  in  a  filter  press  before  drying.  Silver 
oxide  may  be  precipitated  by  caustic  soda,  but  with  copper,  sodium  carbonate 
must  be  used,  the  copper  carbonate  passing  into  the  oxide  during  the  drying. 
Both  silver  and  copper  oxides  may  be  used  in  the  catalyst.  Certain  other  oxides, 
such  as  iron  oxide,  may  be  tolerated  in  limited  amounts  and  appear  to  act  only 
as  diluents.  When  properly  prepared,  these  catalysts  will  bring  about  the  com- 
plete oxidation  of  carbon  monoxide  provided  a  sufficient  amount  of  oxygen  is 
present  in  the  mixture.  Moisture  is  rapidly  absorbed  by  the  catalyst,  diminish- 
ing its  activity,  hence  the  gas  mixture  must  be  relatively  dry  for  the  oxidation 
to  be  catalytic.  —  J.  C.  W.  FRAZER. 

33  NAUMANN,  MOESER,  and  LINDENBAUM,  /.  prakt.  Chem.  (2),  75,  146  (1907). 

34  Vanadium  pentoxide  is  an  excellent  catalyst  for  the  oxidation  of  toluene 
to  benzaldehyde,  anthracene  to  anthraquinone,  naphthalene  to  phthalic  anhy- 
dride and  other  reactions  of  a  similar  nature. 

Phthalic  anhydride  is  produced  in  America  almost  exclusively  by  this  proc- 
ess. Naphthalene  is  volatilized  in  an  air  stream  and  passed  over  the  catalyst. 
The  reaction  begins  at  about  300°  and  attains  a  maximum  yield  at  about  400  to 
450°,  equaling  about  50%  of  the  theoretical.  [  GIBBS,  J.  Ind.  Eng.  Chem.,  n,  1031 
(1919)]. 

Vanadium  compounds  have  been  extensively  employed  in  the  production  of 
aniline  black.  [PINKNEY,  Brit.  pat.  2745  of  1871,  See  Chem.  News,  33,  116 
(1876)]. 

Austerweil  (U.  S.  pat.  979,247  (1910);  C.  A.,  5,  972)  used  vanadium  com- 
pounds in  solution  to  catalyze  the  oxidization  of  borneol  to  camphor  by  nitric 
acid.  —  H.  D.  GIBBS. 

36  Recently  the  oxidation  of  benzene  vapors  by  air  in  the  presence  of 
vanadium  pentoxide  has  assumed  commercial  importance  as  a  method  for  manu- 
facturing malei'c  acid,  WEISS  and  DOWNS,  /.  Ind.  Eng.  Chem.,  12,  228  (1920), 
V.  S.  patents  1,318,631-2-3,  Oct.  14,  1919,  C.  A.,  14,  70;  Can.  pat.  192,766,  Sept. 
16,  1919,  C.  A.,  13,  2683.  — E.  E.  R. 

36  JOHNSON,  English  patent  17,424  of  1911;  /.  Soc.  Chem.  Ind.,  31,  772  (1912). 

87  FARBW.  MEISTER,  Lucius  and  BRUNING,  English  patent  10,377  of  1914, 
/.  Soc.  Chem.  Ind.,  33,  961  (1914). 


97  OXIDATIONS  264 

The  use  of  cerium  oxide  permits  acetic  acid  being  made  from  ace- 
tylene in  one  operation  by  effecting  the  hydration  (309)  and  oxidation 
simultaneously.  It  is  sufficient  to  circulate  a  mixture  of  130  parts 
acetylene  and  80  to  100  parts  oxygen  through  a  mixture  of  400  parts 
glacial  acetic  acid,  100  parts  water,  50  parts  mercuric  nitrate,  and 
10  parts  cerium  oxide  kept  between  50  and  100°. 38 

262.  Anthracene  can  be  transformed  directly  into  anthraquinone 
by  gaseous  oxygen  under  pressure  and  in  the  presence  of  catalysts.39 
Osmium  peroxide  in  the  small  amount  of  0.05%  realizes  this  oxida- 
tion rapidly  with  oxygen  under  10  atmospheres  pressure.40    The  same 
result  can  be  obtained  by  keeping  anthracene  suspended  in  30  parts 
water  containing  a  little  ammonia  and  0.5  part  copper  oxide  for  20 
hours  at  170°  with  compressed  oxygen.41 

The  mixture  of  oxides  remaining  from  the  manufacture  of 
Welsbach  incandescent  mantles  has  been  proposed  as  a  catalyst  for 
direct  oxidation.42 

263.  Metallic  Chlorides.    Anhydrous  aluminum  chloride,  A1C13, 
causes  the  direct  fixation  of  atmospheric  oxygen  by  aromatic  hydro- 
carbons.   Benzene  gives  a   certain  amount  of  phenol   and  toluene 
yields  m.cresole.43 

264.  Manganous  Salts.    As  has  been  stated  in  Chapter  III  (153), 
manganous  salts  are  active  agents  of  direct  oxidation,  particularly  in 
water  solution.    This  activity  persists  whatever  be  the  acid  constit- 
uent of  the  salt;   it  is  observed  in  the  salts  of  mineral  acids,   in  the 
acetate,  butyrate,  benzoate  and  oxalate:    it  is  sixteen  times  as  great 
in  the  succinate  as  in  the  nitrate.    We  can  assume  that  the  manganous 
salt  is  partially  hydrolyzed  in  water  solution  and  that  the  resulting 
manganous  hydroxide  is  oxidised  to  the  dioxide  by  one  atom  of  an 
oxygen  molecule,  the  other  oxidising  the  organic   compound.    The 
nascent  manganese  dioxide,  in  turn,  would  part  with  its  extra  oxygen 
to   another  portion  of  the   organic   compound   and  the  manganous 
hydroxide  thus  regenerated  would  begin  the  cycle  again.    A  trace 
of  the  manganous  salt  would  thus  be  able  to  oxidise  an  unlimited 
amount  of  the  oxidisable  substance.44 

38  DREYFUS,  French  patent  479,656,  J.  Soc.  Chem.  Ind,,  35,  1179  (1916). 

39  The  best  catalyst  yet  found  for  oxidising  anthracene  to  anthraquinone  is 
vanadic  oxide.    The  conditions  are  about  the  same   as  for  the   oxidation   of 
naphthalene  to  phthalic  anhydride.  — H.  D.  GIBBS. 

*°  HOFMANN,  Berichte,  45,  3329  (1912). 

41  German  patent,  292,681. 

42  MASON  and  WILSON,  Proc.  Chem.  Soc.,  21,  296  (1905);  C.,  1906  (1),  395. 
*3FRiEDEL  and  CRAFTS,  Ann.  Chim.  Phys.  (6),  14,  435  (1888). 
"BERTRAND,  Bull.  Soc.  Chim.  (3),  17,  753  (1897). 


265  CATALYSIS  IN  ORGANIC  CHEMISTRY  98 

Cerium  salts  may  frequently  act  similarly   (153). 

265.  Oxidation  of  Oils.     The  bleaching  of  oils  can  be  effected 
by  a  moderate  oxidation  with  warm  air  in  the  presence  of  catalytic 
oxides  which   doubtless   act  after   being  transformed   into   metallic 
soaps,  the  true  decolorizers. 

Palm  oil  through  which  a  current  of  air  is  passed  at  80-90°  is 
bleached  in  four  hours  if  0.2%  manganese  borate  is  added.  The  same 
oil  with  0.1%  cobalt  borate  is  bleached  in  3.5  hours  by  the  passage 
of  less  than  its  own  volume  of  air.  With  the  same  proportion  of 
nickel  or  iron  borate,  about  three  times  as  much  air  and  10  hours 
are  required.45 

If  the  operation  is  carried  on  in  an  autoclave  with  compressed  air, 
the  addition  of  0.02%  of  cobalt  soap  permits  various  oils  to  be 
bleached  perfectly  and  rapidly.46 

266.  The  so-called  drying  oils,  such  as  linseed  and  poppy  seed, 
have  the  property  of  rapidly  becoming  thick  jin  contact  with  air, 
which  oxidises  them,  converting  them  into  resinous  substances  which 
are  almost  insoluble  in  boiling  alcohol.     It  has  long  been  known  that 
this  drying  power,  depending  on  the  oxidisability,  is  greatly  increased 
by  incorporating  with  the  oils  small  proportions  of  salts  of  lead  and 
particularly  of  manganese,  the  important  accelerating  agent  appearing 
to  be  the  metallic  soap  formed  with  the  oil.47 

The  metallic  soaps  that  are  the  most  active  are  those  containing 
metals  which  are  capable  of  several  degrees  of  oxidation,  particularly, 
cobalt,  manganese,  cerium,  lead,  chromium,  iron,  and  uranium,  while 
soaps  containing  bismuth,  aluminum,  mercury,  and  thallium  are  less 
active.48 

The  direct  oxidation  of  oils  is  retarded  by  moisture  and  accelerated 
by  light.  Elevation  of  temperature  and  increase  of  the  pressure  of 
the  oxygen  increase  the  velocity  of  the  oxidation.49 

267.  Metallic  Silicates.    Silicates  can  sometimes  be  substituted 
for  the  corresponding  oxides.     Kaolin  (aluminum  silicate)  causes  the 
union  of  hydrogen  and  oxygen  at  230°. B0 

45  SASTRY,  J.  Chem.  Soc.,  107,  1828  (1916). 

46  RAI,  J.  Soc.  Chem.  Ind.,  36,  948  (1917). 

47  LIVACHE,  Compt.  rend.,  124,  1520  (1897);  C.,  1897  (2),  332. 

48  MACKEY  and  INGLE,  J.  Soc.  Chem.  Ind.,  36,  317  (1917). 

49  FOKIN,  Z.  angew.  Chem.,  22,  1451  (1909). 

«o  JOANNIS,  Compt.  rend.,  158,  501  (1914) ;  C.  A.,  9,  1866. 


OXIDATIONS  269 


II.  —  Oxidations   Carried   Out  with   Oxidising  Agents 

268.  Oxidations  by  Hydrogen  Peroxide.    The  oxidation  of  or- 
ganic compounds  by  hydrogen  peroxide  can  be  advantageously  cat- 
alyzed by  small  quantities  of  ferrous  or  ferric  salts  (acetate).61 

Methyl,  ethyl,  propyl,  butyl,  isobutyl,  and  isoamyl  alcohols  are 
oxidised  to  a  mixture  of  aldehyde  and  acid,  the  acid  being  more 
abundant  when  ferrous  oxalate  is  used  than  with  the  sulphate.  The 
addition  of  wood  charcoal  favors  the  production  of  aldehyde.  Man- 
ganous  salts  can  be  substituted  for  the  iron.62 

Glycol  furnishes  glycolic  aldehyde  without  any  glyoxal.63 
Glycerine  reacts  vigorously  to  give  glyceric  aldehyde,  along  with  a 
little  dihydroxy -acetone.541  Arabite  yields  an  araboketose  and 
dulcite,  galactose.55  Malic  acid  passes  into  oxalacetic  acid,  H02C  .- 
CO  .  CH2 .  C02H.66 

Benzene  is  partially  transformed  into  phenol  and  then  to  pyro- 
catechol; 57  p.hydroxybenzaldehyde,  HO  .  C6H4 .  CHO,  gives  proto- 
catechuic  aldehyde.58 

Amines  likewise  undergo  a  regular  oxidation  to  the  corresponding 
aldehydes  when  they  are  warmed  above  50°  with  hydrogen  peroxide  in 
presence  of  a  ferrous  salt;  ethylamine  giving  acetaldehyde;  isoamyl- 
amine,  isovaleric  aldehyde;  benzylamine,  benzaldehyde,  while  amino- 
ethyl  alcohol  is  changed,  above  30°,  to  a  mixture  of  glycolic  aldehyde 
and  glyoxal.™ 

The  use  of  the  double  cyanide  of  copper  and  potassium  permits 
the  oxidation  of  morphine  hydrochloride  by  hydrogen  peroxide  to 
dehydromorphine  and  pseudomorphine.™ 

Furfural  in  alcoholic  beverages  can  be  destroyed  slowly  by  the 
addition  of  1%  hydrogen  peroxide  and  0.01%  manganese  acetate.6* 

269.  Oxidation  by  Nitric  Acid.     Vanadium  pentoxide,  employed 

51  FENTON,  J.  Chem.  Soc.,  65,  899  (1894). 

52  DOROSHEVSKII  and  BARDT,  J.  Russian  Phys.  Chem.  Soc.,  46,  754  (1914); 
C.  A.,  9,  1865. 

53  FENTON  and  JACKSON,  J.  Chem.  Soc.,  75,  575  (1899). 
"FENTON  and  JACKSON,  Ibid.,  75,  1  (1899). 

55  NEUBERG,  Berichte,  35,  962  (1902). 

56  FENTON  and  JONES,  J.  Chem.  Soc.,  77,  69  (1900)  and  79,  91  (1901). 

57  CROSS,  BEVAN  and  HEIBERG,  Berichte,  33,  2015  (1900). 
68  SOMMER,  German  patent,  155,731,  C.,  1904  (2),  1631. 

59  SUTO,  Biochem.  Zeitschr.,  71,  169  (1915);  C.  A.,  9,  3059. 

60  DENIGES,  Bull.  Soc.  Chim.  (4),  9,  264  (1911). 

61  CHAUVIN,  Ann.  Falsij.,  6,  463  (1913) ;  C.  A.,  8,  981. 


269  CATALYSIS  IN  ORGANIC  CHEMISTRY  100 

in  the  ratio  of  0.1  g.  to  50  g.  cane  sugar  and  500  cc.  nitric  acid  (density 
1.4)  causes  the  complete  oxidation  of  the  sugar  in  20  to  30  hours  in 
the  cold  to  oxalic  acid  without  the  formation  of  saccharic,  mucic, 
tartaric  acids,  etc.,  as  by-products.  Above  70°,  carbon  dioxide  and 
water  are  obtained  instead  of  oxalic  acid.62 

In  the  presence  of  mercuric  nitrate,  nitric  acid  oxidises  anthracene 
to  anthraquinone.  The  reaction  is  finished  in  three  hours  if  117  parts 
anthracene  suspended  in  300  parts  nitrobenzene  are  warmed  to  30° 
with  460  parts  31%  nitric  acid  in  which  three  parts  of  mercury  have 
been  dissolved.63 

In  the  nitration  of  aromatic  compounds  by  mixtures  of  nitric  and 
sulphuric  acids,  the  presence  of  a  mercuric  salt  has  no  influence,  but 
with  nitric  acid  of  density  1.3,  it  causes  oxidation  along  with  nitra- 
tion or  the  substitution  of  a  nucleus  hydrogen  by  the  phenolic  hy- 
droxyl  group.  Thus  benzene,  toluene,  and  ethyl-benzene  give  nitro- 
phenols.  It  is  possible  to  prepare  2,4-dinitrophenol  and  picric  acid 
by  heating  benzene  on  the  steam  bath  under  reflux  with  8  times  its 
weight  of  nitric  acid,  density  1.3,  and  15%  mercuric  nitrate.  The 
oxidation  must  precede  the  nitration,  since  nitrobenzene  is  not  oxidised 
by  this  treatment.6465 

62  NAUMANN,  MOESER,  and  LINDENBAUM,  J.  prakt.  Chem.  (2),  75,  148  (1907). 

63  U.  S.  patent,  119,546. 

64  WOLLFENSTEIN  and  BOTERS,  Berichte,  46,  586  (1913). 

65  In  addition  to  vanadium  and  mercury  compounds,  a  number  of  other 
substances  have  been  found  to  accelerate  oxidation  by  nitric  acid.    Disregarding 
the  mechanism  of  reaction,  oxides  of  nitrogen  and  nitrous  acid  may  be  con- 
sidered as  catalysts  for  oxidation  by  nitric  acid.    For  instance,  VELEY  (Proc.  Roy. 
Soc.,  48,  45&-9  (1891)  )  found  that  the  presence  of  nitrous  acid  initiated  the  oxi- 
dation of  copper,  mercury  and  bismuth  by  30%  nitric  acid.    Oxides  of  nitrogen 
are  mentioned  a  number  of  times  in  the  patent  literature  as  being  necessary  or 
desirable  for  the  purpose  of  starting  oxidation  of  organic  compounds  by  nitric 
acid,    especially    in   the    manufacture    of    camphor.    Molybdenum    compounds, 
salts  of  manganese,  iron,  cerium  and  palladium,  and  even  salts  of  calcium  and 
magnesium  have,  under  various  conditions,  been  found  to  accelerate  oxidations 
by  nitric  acid.    Probably,  in  many  cases,  the  acceleration  produced  by  foreign 
substances  is  due  to  the  reducing  action  of  the  substance  on  the  nitric  acid,  with 
consequent  formation  of  oxides  of  nitrogen.    Thus  the  Commercial  Research 
Company  proposes  to  start  the  oxidizing  action  of  nitric  acid  on  aromatic  hydro- 
carbons with  side  chains  by  means  of  formaldehyde,  copper,  zinc,  starch  or  other 
reducing  substance  (Brit.  Pat.,  141,333  (1920)  ). 

Nitration  by  means  of  nitric  acid  is  likewise  accelerated  by  dissolved  oxides 
of  nitrogen.  KLEMENC  and  EKL  (Monatsh.  39,  641-98  (1918)  )  studied  the  nitra- 
tion of  a  number  of  phenol  derivatives  and  concluded  that  pure  nitric  acid, 
free  from  dissolved  nitrogen  peroxide  or  nitrous  acid,  does  not  cause  nitration. 

HOLDERMANN  (Berichte,  39,  1250  (1906)  )  obtained  negative  results  in  efforts 
to  influence  the  position  of  the  entering  nitre-groups  by  nitrating  in  the  pres- 


101  OXIDATIONS         ,>>    t         \_/f 

270.  Oxidations  by  Hypochlorites.  The  additfoir  of  a  ''very 
small  amount  of  a  cobalt  or  nickel  salt  to  a  solution  of  an  alkaline 
hypochlorite,  or  chloride  of  lime,  causes  the  evolution  of  oxygen  in 
the  cold.66 

This  oxidising  mixture  may  be  used  for  oxidising  organic  sub- 
stances. It  transforms  o.nitrotoluene  into  o.nitrobenzaldehyde  and 
acid.67 

By  the  same  means,  phenanthridene  is  oxidised  to  phenanthri- 
done:  68 

C6H4  -  CH  C6H4  -  CO 

CH4  -  N  CeH4  -  NH 


and  acridine  into  acridone: 


/CHV  /C0\ 

4x          ^CeHi    —  »    CeH^  x 

\N  /  \NH/ 


271.  Oxidations  by  Chlorates.  The  oxidation  of  aniline  hydro- 
chloride,  in  the  preparation  of  aniline  black,  is  carried  out  in  the  cold 
by  a  solution  of  potassium  or  sodium  chlorate  with  the  aid  of  metal 
catalysts,  the  most  active  of  which  is  vanadium  pentoxide,  V205,  of 
which  one  part  is  sufficient  for  270,000  parts  of  aniline  and  the  corre- 
sponding amount  of  chlorate.  Salts  of  cerium  and,  to  a  less  extent, 
those  of  copper  and  iron  are  useful  catalysts  but  less  powerful. 

Osmium  peroxide,  Os04,  is  at  least  as  powerful  as  vanadium  pent- 


ence  of  catalysts,  but  an  appreciably  greater  yield  of  dinitrobenzene,  from  nitro- 
benzene, was  obtained  by  nitrating  with,  rather  than  without,  a  small  amount 
of  mercuric  nitrate,  under  conditions  otherwise  similar  (28.0%  and  23.5%  of 
theory  respectively).  Also,  Holdermann  obtained  evidence  that  mercuric  ni- 
trate acts  as  catalyst  in  the  nitration  of  beta-methylanthraquinone.  For  the 
control  of  the  position  of  the  entering  nitro-group,  the  use  of  considerable  quan- 
tities of  different  acids  mixed  with  the  nitric  acid  is  more  promising  than  the 
use  of  small  amounts  of  metal  salts.  See  TINGLE  and  BLANCK  (/.  Amer.  Chem. 
Soc.,  30,  1395  and  1587  (1908)  ). 

Additional  data  on  simultaneous  nitration  and  oxidation  in  the  presence  of 
mercury  compounds  are  given  by  WOLFFENSTEIN  and  PAAB  (Berichte,  46,  589 
(1913)  )  and  VIGNON  (Bull.  Soc.  Chim.,  27,  547-50  (1920) ).  There  are  also  a 
number  of  patents  on  this  subject.  Silver,  copper  and  aluminum  salts  are  said 
to  act  as  catalysts  as  well  as  mercury.  —  A.  S.  RICHARDSON. 

66  FLEITMANN,  Annalen,  134,  64  (1865). 

67  BADISCHE,  German  patent,  127,388,  C.,  1902  (1),  150. 

68  PICTET  and  PATRY,  Berichte,  26,  1962  (1893). 


272     v,        ^CATALYSIS  IN  ORGANIC  CHEMISTRY  102 

oxide  and  its  use  makes  it  possible  to  oxidise  anthracene  to  anthra- 
quinone  by  means  of  chlorates.69 

272.  Oxidations  by  Sulphur  Trioxide.     Fuming  sulphuric  acid 
is  frequently  used  as  an  oxidiser  for  organic  compounds,  the  trioxide 
being  reduced  to  the  dioxide,  but  its  action  is  not  rapid  enough  in  the 
absence  of  metallic  catalysts,  the  most  active  being  mercuric  sulphate 
between  290  and  390°. 70    The  sulphates  of  potassium,  magnesium, 
manganese,  and  cobalt  are  without  effect,  while  those  of  nickel  and 
iron  act  feebly.    Only  the  sulphate  of  copper  can  replace  that  of  mer- 
cury in  practice  but  it  is  disadvantageous.    It  should  be  mentioned 
that  a  mixture  of  the  sulphates  of  copper  and  mercury  is  more  active 
than  the  two  taken  separately.71 

It  has  been  proposed  to  add  to  the  sulphuric  acid  the  mixture  of 
the  rare  earths  (oxides  of  cerium,  lanthanium,  etc.)  which  is  a  by- 
product in  the  manufacture  of  thorium  nitrate,  but  this  has  not  proved 
to  be  of  any  advantage.72 

In  the  Kjeldahl  method  for  estimating  nitrogen  in  organic  com- 
pounds, the  substances  are  boiled  for  a  long  time  with  fuming  sul- 
phuric acid.  During  the  oxidation  of  the  carbon  and  hydrogen,  all 
the  nitrogen  passes  into  ammonia  which  is  retained  by  the  sulphuric 
acid  without  being  burned.  The  addition  of  0.5%  mercuric  sulphate 
triples  the  speed  of  the  oxidation.73  In  practice,  1  to  2  g.  of  mercury 
to  20  cc.  acid  is  used  for  5  to  7  g.  of  sample  to  be  analyzed. 

273.  The  chief  application  of  oxidation  by  fuming  sulphuric  acid 
is  the  preparation  of  phthalic  acid  from  naphthalene,  a  reaction  which 
is  the  basis  of  one  of  the  methods  for  making  artificial  indigo.74 
When  naphthaline  is  moderately  heated  with  the  acid,  sulphonation 
takes  place,  but  above  200°  oxidation  sets  in.    At  275°  the  oxidation 
rate  is  quintupled  by  1%  of  mercuric  sulphate.75 

274.  In  the  presence  of  mercuric  sulphate,  fuming  sulphuric  acid 
can  oxidise  anthraquinone  and  further  oxidise  the  hydroxyanthra- 
quinones  first  formed.    Thus  anthraquinone   and   1-hydroxy anthra- 
quinone give  quinizarine,  1,4-C14H602(OH)2.76 

At  200-250°,  alizarine  gives  quinalizarine,  1,2,5,8-C14H402(OH)4, 

6*  HOFMANN  and  SCHUMPELT,  Berichte,  48,  816  (1915). 

70  GRAEBE,  Berichte,  29,  2806  (1896). 

71  BREDIG  and  BROWN,  Z.  physik.  Chem.,  46,  502  (1903). 
™  DITZ,  Chem.  Zeit.,  29,  581  (1905);  C.,  1905   (2),  485. 

73  WILFARTH,  Chem.  Centr.,  1885,  17  and  113. 

74  BADISCHE,  German  patent,  91,202. 

75  This  process  is  being  replaced  by  the  high  temperature  air  oxidation 
process.    See  note  to  260  supra.  —  H.  D.  GIBBS. 

76  WACKER,  /.  prakt.  Chem.  (2),  54,  88  (1896). 


103  OXIDATIONS  277 

and  1,3,5,7-tetrahydroxyanthraquinone  heated  with  20  parts  of  sul- 
phuric acid  of  66°  Be.  to  the  same  temperature  in  the  presence  of  0.05 
part  mercuric  sulphate,  yields  1,3,4,5,7,8-hexahydroxyanthraquinone 
or  anthracene  blue.  The  addition  of  boric  acid  greatly  favors  these 
reactions. 

275.  Oxidations  by  Permanganates.     The  oxidation  of  aliphatic 
alcohols  by  potassium  permanganate  in  presence  of  ferrous  sulphate 
readily  gives  aldehydes  but,  on  the  contrary,  in  the  presence  of  ferrous 
oxalate,  the  acids  are  formed  quantitatively.77 

276.  Oxidations  by  Persulphates.     The  persulphates  of  the  alka- 
lies mixed  with  nitric  acid  and  a  small  quantity  of  silver  nitrate  are 
useful  for  oxidising  organic  compounds.     The  active  agent  is  a  silver 
peroxide  or  pernitrate  which  is  constantly  regenerated  by  the  per- 
sulphate.78 

Benzene  is  transformed  into  quinone  by  this  means,  and  oxalic  acid 
is  burned  to  carbon  dioxide.  Quinone  is  broken  up  into  a  number  of 
products  among  which  is  found  maleic  acid.79 

277.  Oxidations  by  Nitrobenzene.     In  the  dye  industry  nitro- 
benzene is  frequently  used  as  an  oxidising  agent,  being  reduced  to 
aniline;  the  presence  of  ferrous  salts  aids  in  these  oxidations. 

77  DOROSHEVSKII  and  BARDT,  J.  Russian  Phys.  Chem.  Soc.,  46,  754  (1914) ; 
C.  A.,  9,  1865. 

78  KEMPF,  Berichte,  38,  3963  (1905).    BABOROVSKY  and  KUZMA,  Z.  Elektroch., 
14,  196  (1908). 

™  KEMPF,  Berichte,  39,  3715  (1906). 


CHAPTER  VI 
VARIOUS    SUBSTITUTIONS    IN   MOLECULES 

§  i.  — INTRODUCTION    OF    CHLORINE,    BROMINE 
AND   IODINE 

Chlorinations 

278.  The  presence  of  anhydrous  chlorides  is  a  great  aid  in  the 
direct  chlorination  of  organic  compounds,  whether  the  chlorides  are 
added  as  such  or  as  the  elements  which  are  immediately  transformed 
into  the  chlorides  by  the  chlorine.    There  is  no  need  to  distinguish 
between  these  two. 

Iodine  or  Iodine  Chloride.  Iodine,  or  iodine  monochloride,  in 
presence  of  an  organic  substance  and  of  chlorine  is  changed  to  the 
trichloride  which  gives  up  chlorine  to  the  organic  substance,  being 
itself  reduced  to  the  monochloride  which  starts  all  over  again.  With 
2  to  12%  of  iodine  it  is  easy  to  chlorinate  benzene*  toluene,2  the 
xylenes?  etc.,  and  also  to  transform  carbon  disulphide  into  carbon 
tetrachloride.4  5 

The  chlorine  compounds  thus  obtained  are  always  mixed  with 
a  small  amount  of  iodine  derivatives  formed  by  catalytic  induction. 

279.  Bromine.    This    can    catalyze    chlorinations    in   the    same 
manner  as  iodine,  particularly  in  the  preparation  of  carbon  tetra- 
chloride from  the  disulphide,  but  its  use  is  less  advantageous. 

280.  Sulphur.    The  immediate  chlorination  of  sulphur  by  chlo- 
rine to  several  degrees  of  chlorination  makes  of  it  a  good  chlorinating 
agent  of  moderate  activity  which  gives  excellent  results  in  some 
cases.    Thus  to  transform  acetic  acid  into  chloracetic,  chlorine  is 

1  MULLER,  J.  Chem.  Soc.,  15,  41  (1862) ;  Jahresb.,  1862,  414  and  1864,  524. 
JUNGFLEISCH,  Ann.  Chim.  Phys.  (4),  15,  186  (1868). 

2  BEILSTEIN  and  GEITNER,  Annalen,  139,  334  (1866).    LIMPRICHT,  Ibid.,  139, 
326  (1866).    HUBNER  and  MAJERT,  Berichte,  6,  790  (1873). 

8  WOLLRATH,  Zeit.  j.  Chem.,  1866,  488.  KRUGER,  Berichte,  18,  1755  (1885). 
KLUGE,  Ibid.,  18,  2099  (1885).  KOCH,  Ibid.,  23,  2319  (1890). 

*  English  patent,  18,890  of  1899. 

5  With  iodine  as  a  catalyst,  the  reaction  may  be  stopped  at  the  inter- 
mediate stage,  ClgCSCl,  though  with  iron,  carbon  tetrachloride  is  formed  at 
once.  (HELFRICH  and  REID,  J.  Amer.  Chem.  Soc.,  43,  593  (1921)).  — E.  E.  R. 

104 


105  VARIOUS  SUBSTITUTIONS  IN  MOLECULES  282 

passed  into  the  boiling  acid  containing  a  small  amount  of  sulphur. 
In  two  hours  8  parts  of  acetic  acid  are  changed  to  10  parts  chloracetic 
containing  but  little  acetyl  chloride.  In  the  cold,  with  a  little  sul- 
phur or  sulphur  chloride,  only  acetyl  chloride  is  obtained.6 

281.  Phosphorus.     Red  phosphorus  can  be  substituted  for  sul- 
phur in  the  preparation  of  chloracetic  acid  (280). 

The  presence  of  phosphorus  trichloride  greatly  facilitates  the 
formation  of  benzyl  chloride  from  toluene.  By  passing  a  current  of 
chlorine  into  100  parts  of  boiling  toluene  containing  1  part  phos- 
phorus trichloride  (as  far  as  possible  in  the  sunlight),7  80  parts  of 
the  desired  product  are  obtained  in  eight  hours. 

282.  Charcoal.     Wood  charcoal  readily   causes  the   chlorination 
of  hydrogen  to  hydrochloric  acid  without  explosion.    By  passing  a 
mixture  of  equal  volumes  of  carbon  monoxide  and  chlorine  through 
a  long  tube  filled  with  fragments  of  charcoal,  carbonyl  chloride  is  ob- 
tained.8   Animal  black  gives  even  better  results,  a  30  cm.  tube  being 
sufficient.9  10 

A  charcoal  made  by  calcining  blood  with  potassium  carbonate 
can  serve  as  a  catalyst  for  the  chlorination  of  organic  substances 
between  250°  and  400°.  The  progressive  and  complete  chlorination 
of  ethyl  chloride  can  thus  be  readily  obtained.11 

Carbon  can  likewise  serve  as  a  catalyst  in  the  preparation  of 
carbon  tetrachloride  from  carbonyl  chloride  by  a  kind  of  auto-chlori- 
nation: 


The  carbonyl  chloride  vapors  are  passed  through  a  succession  of 
towers  filled  with  coke  or  animal  charcoal.12 

6  AUGER  and  BEHAL,  Bull.  Soc.  Chim.  (3),  2,  145  (1889).    RUSSANOF,  /.  Rus- 
sian Phys.  Chem.  Soc.,  1891,  1,  222;  Berichte,  25,  Ref.  334  (1892). 

7  If  sunlight  is  used  no  other  catalyst  is  required.    The  chlorine  reacts  as 
fast  as  it  can  be  passed  in,  even  at  0°.  —  E.  E.  R. 

8  SCHIEL,  Jahresb.,  1864,  359. 

9  PATERNO,  Gaz.  Chim.  ItaL,  8,  233  (1878). 

10  Using  10  g.  charcoal  prepared  from  ox  bones,  ATKINSON,  HEYCOCK  and 
POPE  (/.  Chem.  Soc.,  117,  1410  (1920)  )  caused  carbon  monoxide  and  chlorine  to 
combine  at  40  to  50°  as  rapidly  as  the  mixture  could  be  passed  into  the  U-tube 
containing  the  catalyst.    After  the  preparation  of  10  k.  of  phosgene  this  catalyst 
had  lost  none  of  its  activity. 

They  found  the  activated  charcoal  from  Army  box  respirator  to 
be  more  active  still,  it  being  extremely  efficient  even  at  14°.  Even 
at  50°  this  catalyst  does  not  cause  the  formation  of  hydrogen  chloride  in  mix- 
tures of  chlorine  and  carbon  monoxide  containing  hydrogen.  —  E.  E.  R. 

11  DAMOISEAU,  Compt.  rend.,  83,  60  (1876). 

12  U.  S.  patent,  808,100. 


283  CATALYSIS  IN  ORGANIC  CHEMISTRY  106 

283.  Metallic  Chlorides.    Activity  is  possessed  by  the  chlorides 
of  polyvalent  metals  which   have   several   degrees   of   chlorination, 
such  as  iron,  thallium,  molybdenum,  antimony,  tin,  gold,  vanadium, 
uranium,  etc.,  and  also  by  aluminum  chloride  and  to  a  certain  extent 
by  zinc  chloride  but  not  by  the  chlorides  of  the  alkaline  or  alkaline 
earth  metals  or  of  nickel,  cobalt,  manganese  or  lead.13 

Moisture  is  usually  unfavorable  to  their  action. 

284.  Aluminum    Chloride.    Anhydrous    aluminum    chloride,  or 
aluminum  turnings,  is  an  excellent  chlorination  catalyst.14    It  readily 
realizes  the  transformation  of  carbon  disulphide  into  carbon  tetra- 
chloride.15    The  addition  of  3%  of  it  to  benzene  permits  the  progres- 
sive introduction  of  chlorine,  going  from  the  monochlor-  to  hexachlor- 
benzene.17 

A  mixture  of  equal  volumes  of  chlorine  and  carbon  monoxide 
passed  over  fragments  of  anhydrous  aluminum  chloride  at  30-35°, 
is  partially  transformed  into  phosgene.  The  yield  is  better  when  the 
mixture  of  the  gases  is  passed  into  chloroform  saturated  with  alumi- 
num chloride.18 

285.  Ferric  Chloride.    A  little  /erne  chloride,  for  which  may  be 
substituted  iron  scale,  iron  sesquioxide  or  sulphide,  ferrous  carbonate, 
or  even  iron  sulphate,  gives  good  results  with  the  substitution  of 
chlorine  in  aromatic  compounds. 

By  using  one  part  ferric  chloride  and  one  of  iron  powder  to  300 
parts  of  benzene,  one  obtains  a  yield  of  335  parts  of  monochlor- 
benzene  with  37  parts  of  poly-chlor-.19  20 

13  WILLGERODT,  J.  prakt.  Chem.  (2),  34,  264  (1886)  and  35,  391  (1887). 

14  SEELIG,  Annalen,  237,  178  (1887). 

15  GOLDSCHMIDT  and  LARSEN,  Z.  physik.  Chem.,  48,  424  (1904).    BORNWATER 
and  HOLLEMAN,  Rec.  Trav.  Chim.  Pays-Bos,  31,  221  (1912). 

16  MOUNEYRAT,  Bull.  Soc.  Chim.  (3),  19,  262  (1898). 

17  MOUNEYRAT  and  POURET,  Compt.  rend.,  127,  1026  (1898);  C.,  1899  (1),  199. 

18  PLOTNIKOV,  J.  Russian  Phys.  Chem.  Soc.,  48,  457  (1916). 

19  FAHLBERG,  LIST  &  Co.,  German  patent,  219,242. 

20  It  is  usually  assumed  that  the  action  of  ferric  chloride  depends  on  the 
polyvalency  of  iron,  supposing  that  a  part  of  its  chlorine  is  abstracted  by  the 
benzene  leaving  ferrous  chloride  which  then  combines  with  free  chlorine  to  re- 
generate the  ferric  chloride. 

In  order  to  find  whether  benzene  actually  takes  chlorine  away  from  ferric 
chloride  the  following  experiments  were  tried  in  my  laboratory  by  H.  K.  Parker. 
Ferric  chloride  was  sublimed,  as  it  was  formed,  into  a  dry  flask  which  was  re- 
peatedly evacuated  to  remove  free  chlorine.  To  this  ferric  chloride,  100  g.  of 
benzene  was  added  and  kept  at  40°  for  30  hours,  after  which  water  was  added. 
No  chlorine  was  found  in  the  benzene  layer.  The  water  layer  contained  2.90  g. 
ferric  chloride  and  0.36  g.  ferrous.  Into  a  similar  mixture  of  ferric  chloride  and 
benzene,  dry  chlorine  was  passed  at  40°  for  2  hours  and  extensive  chlorination 


107  VARIOUS  SUBSTITUTIONS  IN  MOLECULES  288 

It  is  equally  satisfactory  for  the  chlorination  of  toluene  21  or  the 
xylenes.22 

The  use  of  ferric  chloride  facilitates  the  commercial  preparation 
of  carbon  tetrachloride  from  carbon  disulphide: 


because  it  catalyzes  the  chlorination  of  the  carbon  disulphide  by  the 
sulphur  chloride  according  to  the  equation: 

CS2  +  2S2C12  =  6S  +  CC14. 

The  reaction  commences  at  60°  and  is  continued  at  the  boiling  tem- 
perature of  the  mixture.23  24 

286.  Molybdenum  Chloride.    Molybdenum  chloride,  MoCl5,  is 
an  excellent  catalyst  in  the  aromatic  series  and,  when  used  to  the 
amount  of  0.5%,  permits  successive  stages  of  chlorination.    Its  use 
is  of  no  advantage  in  the  aliphatic  series.25 

287.  Antimony  Chlorides.    The  chlorides  of  antimony    (which 
can  be  replaced  by  the  powdered  metal  or  by  the  oxide)  are  frequently 
employed  as  carriers  in  chlorinations.    They  are  more  active  than 
iodine  and  permit  the  complete  chlorination  of  benzene.26 

They  are  useful  in  transforming  carbon  disulphide  into  the  tetra- 
chloride.27 

The  successive  use  of  iodine  and  of  antimony  pentachloride 
enables  us  to  pass  directly  from  benzyl  chloride  to  hexachlor-  and 
heptachlortoluene.28 

288.  Tin  Chloride.     Stannic  chloride  (which  can  be  replaced  by 
the  metal  or  the  oxide)  can  also  give  good  effects.29    Its  action,  as 


took  place.    At  the  end  there  was  30  g.  benzene  still  unchlorinated  and  treat- 
ment with  water  showed  only  0.04  g.  ferrous  iron. 

These  experiments  show  that  the  reduction  of  ferric  chloride  by  a  large 
excess  of  benzene  is  very  slight.  It  seems  to  me  best  to  regard  the  action  of 
ferric  chloride  as  analogous  to  that  of  aluminum  chloride  in  this  reaction,  see 
note  to  157.  — E.  E.  R. 

21  SEELIG,  Annalen,  237,  152  (1887). 

22  CLAUS  and  BURSTBBT,  /.  prakt.  Ghent.  (2),  41,  552  (1890). 

23  MULLER  and  DUBOIS,  German  patent,  72,999.    English  patent,  19,628  of 
1893. 

24  With   iron   as   catalyst,   it   is   impossible   to   stop   at   the   intermediate, 
C13CSC1.  — E.  E.  R. 

26  ARONHEIM,  Berichte,  8,  1400  (1875).    SEEUG,  Annalen,  237,  152  (1887). 

26  MULLER,  Zeit.  Chem.  Pharm.,  1864,  40. 

27  HOFMANN,  Annalen,  115,  264  (1860). 

28  BEILSTEIN  and  KTJHLBERQ,  Annalen,  150,  306  (1869). 

29  PETRICOU,  Bull.  Soc.  Chim.  (3),  3,  189  (1890). 


289  CATALYSIS  IN  ORGANIC  CHEMISTRY  108 

without  doubt  is  the  action  of  all  chlorides  used  to  aid  direct  chlori- 
nations,  is  proportional  to  its  concentration.30 

289.  Aluminum  Bromide.    Its  use  permits  the  direct  prepara- 
tion of  per  chlor  ethane  j  CC13 .  CC13,  starting  with  acetylene  tetrabro- 
mide,  CHBr2 .  CHBr2,  or  with  ethylene  bromide.31 

Brominations 

290.  Anhydrous  chlorides  and  bromides  are  more  or  less  active 
agents  in  bromination  just  as  in  chlorination.    The  hydrobromic  acid 
produced  in  the  reaction  is  the  product  most  readily  followed.32 

291.  Iodine.    Iodine,  or  rather  iodine  bromide,  which  is  the  im- 
mediate product,   is   frequently  used   and   leads   especially   to  the 
bromination  of  the  aromatic  nucleus.33 

292.  Manganese.    Powdered  metallic  manganese  is  an  excellent 
catalyst  for  the  bromination  of  benzene,  toluene,  and  xylene.    With 
3  g.  of  the  powdered  metal  and  bromine,  18  g.  benzene  is  completely 
converted  into  monobrombenzene  in  90  hours  in  the  cold,  without  the 
metal  suffering  any  appreciable  attack.34    The  slight  traces  of  bro- 
mide formed  on  the  surface  are  doubtless  sufficient  to  catalyze  the 
reaction. 

293.  Aluminum  Chloride.    A  small  proportion  is  sufficient  to 
effect  the  regular  bromination  of  most  organic  compounds.    Thus 
1  g.  can  cause  the  bromination  of  120  g.  benzene.35 

We  may  put  alongside  of  the  brominations  catalyzed  by  aluminum 
chloride  the  migration,  which  it  causes,  of  the  bromine  of  tri- 
bromphenol  to  benzene,36  or  toluene,37  which  are  thereby  trans- 
formed to  brombenzene  or  m.bromtoluene  with  the  production  of 
phenol. 

Aluminum  bromide  causes  a  regular  bromination  of  toluene.38 
Zinc   Chloride  and   Bromide.    Zinc  chloride  or  metallic  zinc 
which  is  changed  to  the  bromide  may  be  effective.39 

30  GOLDSCHMIDT  and  LARSEN,  Z.  physik.  Chem.,  48,  424  (1904). 

31  MOUNEYRAT,  BuU.  Soc.  Chim.  (3),  19,  262  (1898). 

32  GUSTAVSON,  J.  prakt.  Chem.  (2),  62,  281  (1900). 

33  RILLIET  and  ADOR,  Berichte,  8,   1287   (1875).    JACOBSEN,  Ibid.,   17,  2372 
(1884)  and  18,  359  (1885).    BRUNER,  Chem.  Cent.,  1900  (2),  257. 

34  DUCELLIEZ,  GAY,  and  RAYNAUD,  Bull.  Soc.  Chim.  (4),  15,  737  (1914). 

35  FITTIG,  Annalen,  121,  361   (1862).    LEROY,  Bull.  Soc.  Chim.  (2),  48,  210 
(1887).    Roux,  Ann.  Chem.  Phys.  (6),  12,  347  (1887). 

38  KOHN  and  MULLER,  Monatsh.  Chem.,  30,  407  (1909). 
s^  KOHN  and  BUM,  Ibid.,  33,  923  (1912). 

3*  GUSTAVSON,  J.  Russian.  Phys.  Chem.  Soc.,  9,  286  (1877). 

39  SCHIAPARELLI,  Gaz.  Chim.  ltd.,  11,  70  (1882), 


109  VARIOUS  SUBSTITUTIONS  IN  MOLECULES  296 

Ferric  Chloride  or  Bromide.  Ferric  chloride  or  finely  divided 
iron  (which  changes  to  the  bromide)  is  a  good  bromination  catalyst.40 

CH2  -  CHBr 

Cyclobutene  bromide.  •  •         ,  brominates  in  the  presence  of 

CH2  -  CHBr 

iron  powder  to  tetrabrombutane,  the  ring  being  opened.41 

Mercuric  Chloride  or  Bromide.  These  may  be  used  as  bromi- 
nating  agents.42  Without  doubt  the  simultaneous  formation  of 
aluminum  and  mercuric  bromides  is  the  cause  of  the  remarkable 
activity  of  aluminum  amalgam  as  a  bromination  catalyst.43 


Introduction  of  Iodine 

294.  The  direct  introduction  of  iodine  into  organic  molecules  is 
very  difficult  but  may  sometimes  be  accomplished  by  the  aid  of  ferric 
chloride,  as  is  the  case  with  benzene.  The  yield  of  iodide  thus 
formed  is  low.44 


§2.  —  ADDITION    OF    SULPHUR 

295.  Anhydrous  aluminum  chloride  can  cause  the  addition  of  sul- 
phur to  benzene  at  75-80°.    Thiophenol,  C6H5  .  SH,  and  products 
derived  from  it,  phenyl  sulphide  and  phenylene  sulphide,  are  thus 
obtained.45 

296.  The  direct  sulphuration  of  diphenylamine,  by  heating  the 
amine  with  sulphur,  requires  a  temperature  of  200  to  265°  for  6  to  8 
hours:  4e 


NH(  +  2S  =  H2S  +  S(  )NH. 

\C6H6  \CMS 

In  the  presence  of  iodine  the  reaction  is  complete  in  10  minutes  at 
185°,  giving  a  quantitative  yield  of  thiodiphenyl-amine  instead  of 
50  to  60%.  Thiodinaphthyl  amines,  etc.,  are  also  prepared  in  good 
yields.47 

40  SCHENFELEN,  Annalen,  231,  164  (1885). 

41  WILLSTATTER  and  BRUCE,  Berichte,  40,  3979  (1907). 

42  LAZAREW. 

43  COHEN  and  DAKIN,  J.  Chem.  Soc.,  75,  893  (1899). 

44  LOTHAR  MEYER,  Annalen,  231,  195  (1885). 

48  FRIEDEL  and  CRAFTS,  Bidl.  Soc.  Chim.  (2),  39,  306  (1883). 

48  BERNTHSEN,  Annalen,  230,  77  (1885). 

«  KNOEVENAGEL,  J.  prakt.  Chem.  (2),  89,  11  (1914). 


297  CATALYSIS  IN  ORGANIC  CHEMISTRY  110 

§3.  — ADDITION    OF    SULPHUR    DIOXIDE 

297.  Benzene  warmed  with  aluminum  chloride  absorbs  sulphur 
dioxide  readily  giving  benzene  sulphinic  acid,  C6H5 .  S02H. 48    The 
reaction  is  accelerated  by  the  presence  of  hydrochloric  acid  and  is 
doubtless  due  to  the  formation  of  an  unstable  addition  product  which 
reacts  with  the  benzene  in  the  presence  of  the  aluminum  chloride 
and  hydrochloric  acid.49  \ 

§4.  — ADDITION    OF    CARBON    MONOXIDE 

298.  The  direct  addition  of  carbon  monoxide  to  hydrocarbons  is 
an  exceptional  reaction  which  can  be  realized  in  only  a  small  number 
of  cases.    However,  the  use  of  aluminum  chloride  or  bromide  makes 
it  possible  with  aromatic  hydrocarbons. 

A  mixture  of  carbon  monoxide  and  hydrogen  chloride  is  passed 
for  several  hours  into  benzene  containing  aluminum  chloride  and 
10%  cuprous  chloride  at  40  to  50°. 

It  can  be  assumed  that  the  carbon  monoxide  dissolves  on  account 
of  the  cuprous  chloride  and  forms  formyl  chloride,  H  .  CO  .  Cl,  which 
then  reacts  as  an  acid  chloride  on  the  benzene  in  the  presence  of 
aluminum  chloride  (891).  We  have  in  the  end: 

C6H6  +  CO  =  C6H5 .  CHO. 

The  yield  is  90%. 50    Likewise  from  toluene  and  aluminum  chlo- 
ride, p.toluic  aldehyde,  CH3 .  C6H4 .  CHO,  with  a  yield  of  73%  ;51 
o.Xylene  gives,  by  the  same  method,  1,2  dimethyl-benzaldehyde(±). 
p.Xylene  and  mesitylene  give  analogous  results.52 
The  presence  of  the  cuprous  chloride  and  the  hydrogen  chloride 
seem  to  be  superfluous  and  it  is  sufficient  to  cause  the  carbon  mon- 
oxide under  pressures  of  from  40  to  90  atmospheres  to  act  on  the 
benzene  in  the  presence  of  aluminum  chloride  and  a  little  hydrogen 
chloride.53 

48  FRIEDEL  and  CRAFTS,  Ann.  Chim.  Phys.  (6),  14,  443  (1888). 

49  KNOEVENAQEL  and  KENNER,  Berichte,  41,   3315    (1908).    ANDRIANOWSKI, 
Bull  Soc.  Chim.  (2),  31,  199  and  495  (1879). 

60  REFORMATSKI,  J.  Russian  Phys.  Chem.  Soc.  33,  154  (1901);  C.,  1901  (1), 
1226. 

51  GATTERMANN  and  KOCH,  Berichte,  30,  1623  (1897)  and  GATTERMANN,  Ibid., 
31,  1149  (1898).  English  patent,  13,709  of  1897. 

62  BAYER  AND  Co.,  Chem.  Cent.,  1898,  932.    HARDING  and  COHEN,  J.  Amer. 
Chem.  Soc.,  23,  594  (1901). 

63  English  patent,  3,152  of  1915;  J.  Soc.  Chem.  Ind.,  35,  384  (1916). 


Ill  VARIOUS  SUBSTITUTIONS  IN  MOLECULES  301 

§5.  — INTRODUCTION    OF    METALLIC    ATOMS 
Formation  of  Alcoholates 

299.  Aluminum  alcoholates  are  formed  by  the  direct  action  of 
aluminum  amalgam  on  alcohols  thoroughly  freed  from  water.5*    But 
the  presence  of  a  catalyst  enables  them  to  be  prepared  directly  from 
aluminum.    It  is  sufficient  to  add  a  little  mercuric  chloride,  iodine 
or  even  ethyl  iodide.    Thus  ordinary  absolute  alcohol  readily  gives 
aluminum  ethylate,  A1(OC2H5)3,  a  solid  melting  at  134°  which  can 
be  isolated  by  distilling  at  15  mm.  pressure.55 

Production  of  Mixed  Organo-Magnesium  Compounds 

300.  The  production  of  mixed  organo-magnesium  compounds  from 
organic  halides  is  equivalent  to  the  addition  of  the  magnesium  atom 
to  the  organic  molecule: 

/R 

Mg  +  RBr  =  Mg( 

\Br. 

This  reaction  is  usually  carried  out  in  anhydrous  ether  which 
plays  the  role  of  catalyst  in  their  formation.  It  is  possible  to  carry 
out  the  reaction  in  benzene  in  the  presence  of  a  small  amount  of  ether. 
Without  doubt,  we  have  in  succession: 

C2H5\     /R 
RBr  +  (C2H6)20  =  )0( 

C2H5/  \Br 
and  then: 

C2H5\      /R  /R 

)0(       +  Mg  =  Mg( 
C2HB/     \Br  \Br 

The  regenerated  ether  can  repeat  the  first  reaction. 

301.  The  ethyl  ether  as  catalyst  can  be  replaced  by  other  ethers, 
amyl  ether,  etc.,  or  even  by  a  small  quantity  of  a  tertiary  amine  such 
as  dimethyl  aniline,  the  reaction  taking  place  in  benzene,  toluene, 
hexane,  or  ligroine.    In  this  case  the  temporary   addition  product 
would  be:  56 

C6H6\     /R 
CH3-^N' 
CH3/     \Br. 

54  TISTCHBNKO,  J.  Russian  Phys.  Chem.  Soc.,  31,  483  (1899). 
65  MEISTER,  Lucius  and  BRUNING,  German  patent,  286,596;  /.  Soc.  Chem. 
Ind.,  34,  1168  (1915).  66  TSCHELINZEFF,  Berichte,  37,  4534  (1904). 


302  CATALYSIS  IN  ORGANIC  CHEMISTRY  112 

302.  The  formation  of   organo-magnesium  halides   is   easy  with 
organic  bromides  or  iodides  but  it  is  greatly  facilitated  by  the  pres- 
ence of  a  suitable  catalyst,  iodine,  hydriodic  acid  or  an  alkyl  iodide 
such  as  ethyl  iodide. 

The  addition  of  such  catalysts  is  indispensable  for  the  formation 
of  these  derivatives  from  aliphatic  or  cycloaliphatic  chlorides,  but 
even  with  this  assistance  they  can  not  be  prepared  from  aromatic 
chlorides. 

According  to  Zelinski,  iodine  and  magnesium  produce  in 
anhydrous  ether  some  of  the  compound,  MgI2 .2(C2H5)20,  which  he 
was  able  to  isolate  and  which  would  start  the  reaction.57 

303.  A  certain  number  of  substances  hinder  the  formation  of  the 
organo-magnesium  compounds.    We  may  mention  anisol,  ethyl  ace- 
tate,   chloroform,    and    carbon    disidphide    which    act    as    negative 
catalysts  (11). 

304.  For  the  preparation  of  mixed  organo-zinc  compounds,  Blaise 
uses  pure  ethyl  acetate  as  a  catalyst  instead  of  ether  and  operates 
in  a  toluene  or  petroleum  ether  solution.    Actually  one-third  of  a 
molecule  of  ethyl  acetate  is  used  for  one  molecule  of  the   alkyl 
iodide.58 

67  ZELINSKI,  J.  Russian  Phys.  Chem.  Soc.,  35,  399  (1903). 

68  BLAISB,  Bull  Soc.  Chim.,  1911,  Conference,  7. 


CHAPTER  VII 
HYDRATIONS 

305.  HYDRATION  reactions  can  be  separated  into  two  distinct  groups 
according  to  whether  the  water  is  added  without  splitting  the  mole- 
cule or  whether  the  addition  of  the  water  causes  the  original  molecule 
to  break  up  into  two  or  more  new  ones. 

As  examples  of  the  first  group  we  have  the  addition  of  water  to 
unsaturated  hydrocarbons  giving  alcohols  or  ketones,  or  to  nitrites 
and  imides. 

Reactions  of  the  second  class  are  more  frequent,  such  as  the 
saponification  of  esters,  the  decomposition  of  acetals  and  glucosides, 
the  hydrolysis  of  amides,  oximes,  hydrazones,  semicarbazones,  etc. 

More  or  less  concentrated  mineral  acids  are  very  powerful  agents 
for  realizing  the  various  hydration  reactions,  whether  in  concentrated 
form,  they  give  rise  to  unstable  temporary  addition  products  which 
decompose  to  form  the  hydration  products  and  to  regenerate  the  acids, 
or  whether  they  act  in  dilute  solution  in  consequence  of  their  elec- 
trolytic dissociation,  the  chief  factors  being  the  hydrogen  ions  so 
liberated. 

Water  solutions  of  the  strong  bases,  either  the  alkalies  or  alkaline 
earths,  can  often  realize  hydrations  which  water  alone  can  usually 
accomplish  but  at  a  much  slower  rate  or  a  much  higher  temperature. 

i.  —  Fixation   of    Water   by   Addition 

306.  Ethyl ene  Compounds.     Moderately  concentrated  sulphuric 
acid  enables  us  to  add,  in  the  cold,  a  molecule  of  water  to  isobutylene, 
(CH3)2C:CH2,    to    give    frimethylrcarbinol,    (CH3) . .  COH.1 2    By 
adding  amylene,  little  by  little,  to  a  mixture  of  concentrated  sulphuric 
acid  and  ice,  diluting  with  ice  water,  washing  with  soda,  and  dis- 
tilling the  product,  dimethyl-ethyl  carbinol  is  obtained  with  a  yield 
of  85  to  92%  of  the  amylene.3 

Likewise  3-methylpentene,  CH2  :  CH  .  CH(CH3)  .  CH2 .  CH3,  adds 
water  to  give  the  corresponding  tertiary  alcohol. 

1  BUTLEROW,  Annalen,  144,  22  (1867). 

2  Isopropyl  alcohol  is  now  manufactured  by  absorbing  in  sulphuric  acid 
the  propylene  from  the   gases  resulting   from  the   cracking   of  heavy  hydro- 
carbons.-—E.  E.  R. 

3  ADAMS,  KAMM,  and  MARVEL,  /.  Amer.  Chem.  Soc.,  40,  1950  (1918). 

.113 


307  CATALYSIS  IN  ORGANIC  CHEMISTRY  114 

With  85%  sulphuric  acid  hexene-l  and  heptene-3  give  the 
secondary  alcohols,  accompanied  by  a  certain  amount  of  the  sulphuric 
acid  esters,  while  the  100%  acid  only  polymerizes  the  hydrocarbons.4 

At  45°  sulphuric  acid  effects  the  addition  of  water  to  iso-oleic 
acid  which  is  changed  to  hydroxystearic  acid.5 

307.  Dilute  nitric  acid  provokes  the  rapid  hydration  of  pinene, 
C10H16,   in  alcohol   solution,   at  the  ordinary  temperature  to   form 
terpine,  C10H2002.  6 

Hydrochloric  acid  also  can  cause  the  addition  of  water.  By 
digesting  for  three  hours  in  the  light  a  mixture  of  croton  aldehyde, 
CH3  .  CH  :  CH  .  CHO,  and  hydrochloric  acid,  the  aldol,  /3-hydroxy- 
butyric  aldehyde,  CH3.CH(OH)  .  CH2  .  CHO,  is  formed.7 

308.  Doubly  Unsaturated  Compounds.    Acetylene  hydrocarbons 
and  their  allenic  isomers  can  add  water  in  the  presence  of  sulphuric 
acid  and  other  catalysts  to  give  ketones: 

R.C;  C.R'  +  H20  =  R.CO.CH2.R' 

Rv  /R"  R\  /R" 

and  )C  :  C  :  C(          +  H20  =       ;CH  .CO  .CH( 

R'/  \R'"  R'/  \R'" 

With  sulphuric  acid,  the  reaction  is  carried  out  by  dissolving  the 
hydrocarbon  in  the  cold  concentrated  acid  and  pouring  this  solution 
immediately  on  to  ice.8 

The  mechanism  appears  to  be  the  formation  of  an  unstable  sul- 
phuric acid  derivative  which  decomposes  on  contact  with  water  to 
form  an  unsaturated  alcohol  which'  immediately  isomerizes  into  the 
ketone.  Thus  with  ethyl-acetylene,  we  should  have  successively: 

^CH2 
CH3  .  CH2  .  C  i  CH  +  H2SO4  =  CH3  .  CH2cf 

\O.S03H 


CH3  .CH2  .C  =  H2S04  +  CH3  .CH2  .C(OH)  :  CH2 

\O.S03H 

CH3.CH2C(OH)  :CH2  =  CH3.CH2.CO.CH3. 

In  the  case  of  true  acetylene  hydrocarbons,  the  product  is  a  methyl 
ketone.  With  disubstituted  acetylenes,  two  isomeric  ketones  are  ob- 
tained. This  is  the  case  with  methylamylacetylene.9 

4  BROOKS  and  HUMPHREY,  Ibid.,  40,  822  (1918). 
6  SAYTZEFF,  J.  prakt.  Chem.  (2),  37,  284  (1888). 

6  WIGGERS,  Annalen,  57,  247  (1846). 

7  WURTZ,  Bull.  Soc.  Chim.  (2),  42,  286  (1884). 
*  BEHAL,  Bull.  Soc.  Chim.  (2),  47,  33  (1887). 
9  BEHAL,  Ibid.  (2),  50,  359  (1888). 


115  HYDRATIONS  312 

Acetylene  should  give  acetaldehyde,  but  this  condenses  with  loss 
of  water  (795)  and  crotonic  aldehyde  is  the  chief  product.10 

309.  Water  solutions  of  mercuric  salts,  the  chloride,  bromide,  and 
sulphate,  cause  the  same  formation  of  ketones  in  consequence  of  the 
temporary  production  of  combinations  of  the  hydrocarbon  and  the 
salt,  which  are  then  decomposed  by  water.    Thus  allylene,  CH3  .- 
C  i  CH,  gives  acetone,  CH3 .  CO  .  CH3. 

Acetylene  behaves  normally,  yielding  acetaldehyde: 1X 

CH  !  CH  +  H2O  =  CH3.CHO. 

Acetylene  is  absorbed  at  25  to  45°  in  a  solution  of  mercuric  oxide 
in  water  containing  45%  or,  less  sulphuric  acid,  or  25%  phosphoric 
acid.  The  solution  saturated  with  the  gas  is  warmed  to  80  to  100° 
when  acetaldehyde  is  given  off.  The  solution  is  then  cooled  and 
made  to  take  up  more  gas  and  so  on.  By  a  number  of  repetitions 
the  mercuric  salt  produces  20  times  its  own  weight  of  acetaldehyde.12 
A  stronger  solution  of  sulphuric  acid  is  unfavorable  as  it  would  cause 
the  formation  of  crotonic  aldehyde  and  other  condensation  products. 
(See  the  direct  formation  of  acetic  acid  (261).) 

310.  This  hydration  of  acetylene  to  acetaldehyde  can  likewise  be 
accomplished  by  passing  the  moist  gas  over  zinc,  nickel,  or  ferrous 
oxides  at  300°.    There  is  the  formation  of  a  certain  amount  of  acetal- 
dehyde and  also  of  crotonic  aldehyde.     If  the  moist  acetylene  con- 
tains ammonia,  the  formation  of  acetaldehyde  is  shown  by  the  deposit 
of  crystals  of  aldehyde  ammonia.13 

311.  Nitriles.    Nitrites  dissolved  by  gentle  warming  in  sulphuric 
acid  diluted  with  20%  of  water,  are  transformed  into  amides.    The 
same  transformation  can  be  effected  also  by  caustic  soda  and  potash ; 
but,  especially  if  the  operation  is  carried  on  in  alcohol  solution  in 
the  neighborhood  of  100°,  the  hydration  may  go  so  far  as  to  break 
the  amide  down  into  ammonia  and  the  acid,  which  is  at  least  partially 
neutralized  by  the  alkali. 

312.  Imides.    It    is    the    same    way    with    imides,    succinimide, 
CH2-CO\ 

/I?H,  warmed  with  a  small  amount  of  baryta  water,  gives 
CH2-CO/ 

at    first    amido-succinic    acid,    H2N  .  CO  .  CH2 .  CH2 .  C02H,14    the 
further  hydration  of  which  yields  succinic  acid. 

10  BERTHELOT,  Compt.  rend.,  128,  336  (1899). 

11  KUTSCHEROFF,  Berichte,  17,  13  (1884). 

12  DREYFUS,  French  patent,  487,411  (1918). 

13  CHICHIBABINE,  J.  Russian  Phys.  Chem.  Soc.,  47,  703  (1915) ;  C.  A.,  9,  2512 
(1915). 

14  TEUCHERT,  Annalen,  134,  136  (1865). 


313  CATALYSIS  IN  ORGANIC  CHEMISTRY  116 

H2N.CH-CO\ 

Likewise  aspartic  imide,  /NH,  heated  to  100°  with 

CH2-C(X 

aqueous  ammonia,  adds  a  molecule  of  water  to   give  asparagine, 
HOOC  .  CH2 .  CH(NH2)  .  CONH2.15 

Acetaldehyde  in  water  solution  causes  cyanogen  to  add  two  mole- 
cules of  water  to  form  oxamide,  H2N  .  CO  .  CO  .  NH2.16 

II.  —  Hydrations  with   Decomposition 

313.  A  hydration  which  results  in  the  decomposition  of  the  mole- 
cule is  usually  called  hydrolysis. 


§i.    HYDROLYSIS    IN    WATER    SOLUTION 

Hydrolysis  of  Esters.  The  hydrolysis  of  esters  is  known  as 
saponification. 

When  a  water  solution  of  methyl  acetate  or  ethyl  acetate  is  kept 
in  the  cold,  there  is  a  slow  decomposition  by  water  to  give  the  alcohol 
and  free  acid: 

CH3 .  C02 .  C2H5  +  H20  =  CH3 .  C02H  +  C2H6 .  OH 

The  reverse  reaction  of  esterification  tends  to  reform  the  ester  so 
the  decomposition  is  never  complete;  the  reaction  tends  to  an  equi- 
librium, the  more  water  there  is  present,  the  more  ester  will  be  de- 
composed, but  this  limit  is  not  reached  at  ordinary  temperatures  till 
after  some  years.  In  several  days,  the  amount  of  ester  decomposed 
is  only  about  1%.  On  the  contrary,  if  a  small  amount  of  hydro- 
chloric acid,  or  other  strong  acid,  be  added  to  the  mixture,  the  reaction 
becomes  very  rapid,  the  limit  being  reached  in  24  hours. 

Furthermore,  the  acid  added  is  in  no  way  changed.  It  is  entirely 
precipitated  by  silver  nitrate  which  shows  that  it  has  not  formed  an 
appreciable  amount  of  ethyl  chloride.  Up  to  a  certain  limit,  the 
saponifying  power  of  the  acid  is  proportional  to  its  concentration; 
and  for  different  acids,  at  the  same  molecular  concentrations,  the 
saponifying  power  is  proportional  to  the  strength  of  the  acid  which 
is  measured  by  its  electrolytic  dissociation,  and  consequently  this 
activity  is  defined  by  the  number  of  hydrogen  ions  in  a  unit  volume 
of  the  solution.  Hydriodic,  hydrobromic,  nitric  and  chloric  acids, 
which  are  strongly  ionized,  are  consequently  powerful  catalysts,  and 
so  is  sulphuric  acid  which  is  most  commonly  used  for  this  purpose. 

15  KOERNER  and  MENOZZI,  Gaz.  Chim.  Ital,  17,  173  (1887). 

16  LIEBIG,  Annalen,  113,  246  (1860). 


117  HYDRATIONS  318 

314.  This  action  is  general  and  applies  equally  well  to  the  saponi- 
fication  of  fats  which  are  esters  of  glycerine  with  the  fatty  acids. 
A  fat  heated  with  water  and  4%  sulphuric  acid  to  120°  is  completely 
hydrolyzed  in  12  hours,  42%  of  the  fatty  acids  being  liberated  in  the 
first  hour.    To  produce  a  like  decomposition  with  water  alone  re- 
quires heating  to  220°  in  an  autoclave.17 

315.  In  very  dilute  solutions  the  velocity  of  saponification  is  the 
same  with  hydrochloric,  hydrobromic,  hydriodic,  nitric,  chloric  and 
methyl  sulphuric  acids  of  the  same  acidity  and  is  proportional  to  the 
concentration  of  the  acid. 

It  is  the  same  for  all  the  esters  of  a  given  organic  acid  with  dif- 
ferent primary  alcohols.18 

316.  On  the  other  hand,  the  velocity  changes  greatly  when  the 
organic  acid  from  which  the  ester  is  derived  is  changed.    Thus  for 
ethyl  esters  the  saponification  velocity  of  the  formate  is  25  times 
that  of  the  acetate,  50  times  that  of  the  isobutyrate,  100  times  that 
of  the  valerate,  and  4,000  tunes  that  of  the  benzoate. 

317.  The  presence  of  neutral  metallic  salts  modifies  the  velocity, 
chlorides  accelerating  the  saponification  by  hydrochloric  acid,19  while 
sulphates  retard  the  action  of  sulphuric  acid. 

Pressure  may  also  have  an  effect ;  in  the  case  of  the  saponification 
of  methyl  acetate  by  hydrochloric  acid,  pressure  increases  the  velocity. 

318.  The  soluble  bases,  potassium,  sodium,  barium,  and  calcium 
hydroxides  have  an  analogous  effect  which,  at  first  sight,  would  be 
attributed  to  the  affinity  of  the  base  for  the  acid  liberated,  were  the 
amount  of  ester  saponified  not  disproportionate  to  the  amount  of  base 
reacting.    The  real  reason  for  the  saponification  is  again  found  in 
the  dissociation  of  the  bases  in  dilute  solution  into  ions. 

The  saponification  of  fats  has  given  clear  evidence  on  this  point. 
The  amount  of  lime  required  to  saturate  all  of  the  fatty  acids  of  a 
fat  is  about  9.7%,  and  in  practice  might  reach  12  to  14%,  but  experi- 
ence shows  that  1%  is  sufficient  for  complete  saponification  in  water 
at  190°  under  12  atmospheres  pressure,  while  3%  produces  this  result 
in  8  to  10  hours,  at  170°  and  8  atmospheres.20 

It  appears  from  the  above  figures  that,  in  spite  of  the  additional 
energy  liberated  by  the  combination  of  the  bases  with  the  acids,  the 
catalytic  activity  of  the  bases  is  less  than  that  of  the  strong  acids. 

17  LEWKOWITSCH,  Confer,  a  la  Soc.  Chim.,  1909,  12. 
«  LOWENHERZ,  Z.  phys.  Chem.,  15,  395  (1894). 

i»  TREY,  J.  prakt.  Chem.  (2),  34,  353  (1886),  EULER,  Z.  phys.  Chem.,  33, 
348  (1900). 

20  LPWKOWITSCH,  loc.  cit.f  p.  8. 


319  CATALYSIS  IN  ORGANIC  CHEMISTRY  118 

319.  For  different  strong  bases,  in  very  dilute  solution  and  at  the 
same  concentration,  the  saponification  velocity  is  independent  of  the 
nature  of  the  base,  whether  it  be  potassium,  sodium,  barium  or  cal- 
cium hydroxide,  but  is  proportional  to  the  concentration  of  the  base. 

For  esters  derived  from  the  same  acid,  the  velocity  changes 
greatly  with  the  alcohol,  thus  methyl  acetate  is  saponified  twice  as 
rapidly  by  caustic  soda  in  the  cold  as  is  isobutyl  acetate.2*  The 
influence  of  the  nature  of  the  acid  is  less  than  it  is  in  saponification 
by  strong  acids.  Thus  when  methyl  esters  are  saponified  by  caustic 
soda  at  14°,  the  velocity  for  the  acetate  is  about  double  that  for  the 
isobutyrate,  six  times  that  for  the  isovalerate,  and  quadruple  that 
for  the  benzoate. 

In  the  saponification  of  ethyl  acetate  by  bases,  the  presence  of 
neutral  salts  cuts  down  the  velocity.21 

320.  The  saponification  of  chlorine  derivatives  is  not  usually  pos- 
sible,  but  benzal   chloride  and   benzotrichloride   are   hydrolyzed  to 
benzaldehyde  and  benzoic  acid  by  water  alone  when  heated  under 
pressure. 

The  saponification  of  benzal  chloride,  C6H5CHC12,  by  water  alone 
requires  a  temperature  of  140-160°. 22  In  the  factory  it  is  usually 
effected  by  means  of  milk  of  lime.  In  the  presence  of  iron  powder, 
the  reaction  can  be  carried  out  at  90-95 °.23 

It  is  the  same  way  with  benzotrichloride  which  is  readily  trans- 
formed into  benzoic  acid  in  the  presence  of  iron,  ferric  chloride, 
oxide  or  benzoate.23 

321.  Ethers.    Water  alone  breaks  up  ethers  into  two  molecules 
of  the  alcohols  very  slowly.24    The  addition  of  small  quantities  of 
sulphuric  acid  greatly  accelerates  the  reaction.25 

322.  Acetals.    Acetals  can  be  regarded  as  mixed  ethers  derived 
from  alcohols  and  the  unstable  gylcols  of  which  aldehydes  and  ke- 
tones  are  the  anhydrides.    Their  hydrolysis  cannot  be  accomplished 
by  water  alone,  nor  by  alkalies,  even  when  hot.     On  the  contrary, 
it  is  easily  effected  by  boiling  with  either  dilute  hydrochloric  acid 
or  with  sulphuric  acid  diluted  with  four  volumes  of  water,  the  alde- 
hyde and  the  alcohol  being  set  free. 

323.  Polysaccharides.    Polyoses    and    polysaccharides    such    as 
sucrose,  lactose,  maltose,  trehalose   and  even  starch,   dextrine   and 


21  ARRHENIUS,  Z.  phys.  Chem.,  i,  110  (1887). 

22  LIMPRICHT,  Annalen,  139,  319  (1866). 

23  SCHULTZE,  German  patent,  82,927. 

24  LIEBEN,  Annalen,  165,  136  (1873). 

25  ERLENMEYER,  Zeit.  j.  Chemie,  4,  343  (1868) 


119  HYDRATIONS  326 

cellulose  can  be  regarded  as  ethers  or  acetals  involving  the  many 
alcohol  groups  and  the  aldehyde  or  ketone  groups  of  the  simple 
hexoses.  Their  hydrolysis  into  the  simple  sugars  can  be  realized 
more  or  less  readily  by  the  aid  of  small  quantities  of  acids  as 
catalysts. 

324.  The  inversion  of  cane  sugar,  that  is,  its  complete  hydrolysis 
into  glucose  and  fructose,  can  be  brought  about  by  traces  of  mineral 
acids  and  is,  perhaps,  the  earliest  catalytic  reaction  to  be  observed.26 
Hydrochloric,  sulphuric,  or  even  oxalic  acid  can  be  used  and  the 
velocity  of  the  hydrolysis  is  proportional  to  the  concentration  of  the 
hydrogen  ions  resulting  from  the  electrolytic  dissociation  of  the  acid. 
Concentrated  sugar  solutions  are  rapidly  inverted  by  traces  of  acid. 
A  solution  containing  80  g.  sugar  to  20  g.  water,  with  the  addition 
of  0.004  g.  hydrochloric  acid,  is  completely  inverted  by  boiling  for 
an  hour.27    Even  carbonic  acid  can  cause  this  reaction,  slowly  in  the 
cold,  rapidly  when  heated.    A  sugar  solution  saturated  with  carbon 
dioxide  and  heated  for  an  hour  in  a  sealed  tube  is  completely  in- 
verted.28 

The  velocity  of  the  inversion  of  sugar  by  strong  acids  is  increased 
by  the  addition  of  neutral  salts.29 

When  the  reaction  is  carried  on  in  alcohol  solution,  the  velocity 
varies  considerably  with  the  proportion  and  nature  of  the  solvent.30 
Increase  in  the  concentration  of  the  sugar  increases  the  velocity.31 

High  pressure  diminishes  the  velocity  of  inversion  by  hydrochloric 
acid,  the  diminution  being  about  1%  for  100  atmospheres.32 

325.  The  hydrolysis  of  maltose  is  slower  than  that  of  cane  sugar, 
requiring  at  least  three  hours  of  boiling  with  3%  sulphuric  acid.33 

Trehalose  is  slowly  hydrolyzed  into  glucose  by  warming  with 
dilute  sulphuric  acid.3* 

326.  Sulphuric  acid  diluted  with  33  parts  of  water  is  used  in  the 
commercial  preparation  of  glucose  by  the  hydrolysis  of  starch  at 
100°  for  three  hours.    The  addition  of  a  little  nitric  acid  to  the  sul- 

26  CLEMENT  and  DESORMES,  Ann.  Chim.  Phys.,  59,  329   (1806). 

27  WOHL,  Berichte,  23,  2086  (1890). 

28  LIPPMANN,  Berichte,  13,  1823  (1880). 

29  SPOHR,  Z.  physik.  Chem.,  2,  194  (1888).    ARRHENIUS,  Ibid.,  4,  226  (1889). 
EULER,  Ibid.,  32,  348  (1900). 

so  BURROWS,  J.  Chem.  Soc.,  105,  1260  (1914). 

31  ROSANOFF  and  POTTER,  J.  Amer.  Chem.  Soc.,  35,  248  (1913). 

32  RONTGEN,   Wiedermann's   Annalen    (3),   45,   98    (1892).    ROTHMUND,   Z. 
physik.  Chem.,  20,  170  (1896). 

33  MEISSL,  J.  prakt.  Chem.  (2),  25,  120  (1882). 

34  MUNTZ,  Jahresber.,   1873,  829.    BERTHHLOT,  Ann.   Chim.  Phys.   (3),   55, 
272  (1859). 


327  CATALYSIS  IN  ORGANIC  CHEMISTRY  120 

phuric  acid  seems  to  shorten  the  time  required.  There  is  an  inter- 
mediate formation  of  dextrine  which  is,  in  turn,  hydrolyzed  by  the 
dilute  acid. 

327.  Glucosides.  The  various  substances  designated  by  this  name 
are  numerous  among  vegetable  products  and  have  a  constitution  anal- 
ogous to  that  of  the  polysaccharides.  Their  hydrolysis  by  pure 
water  can  usually  be  accomplished  only  by  heating  to  high  tempera- 
tures in  sealed  tubes,  but  by  boiling  with  dilute  mineral  acids,  they 
are  decomposed  into  a  sugar  (usually  glucose)  and  one  or  more  sub- 
stances of  various  kinds. 

The  action  of  acids  is  comparable  to  that  of  soluble  ferments,  such 
as  emulsine,  but  is  more  rapid  and  more  drastic,  the  product  of  hy- 
drolysis being  sometimes  altered  by  the  peculiar  action  of  the  acid. 

328.  Thus  arbutine   when   boiled   with   dilute   sulphuric   acid   is 
hydrolyzed  into   1  molecule   of   glucose   and   1   molecule   of  hydro- 
quinone,35  which  is  identical  with  the  results  obtained  by  long  con- 
tact with  emulsine  in  the  cold. 

Helicine  is  hydrolyzed  by  dilute  acids  into  glucose  and  salicylic 
aldehyde*6  and  quercitrine  into  isodulcite  and  quercitine  (tetrahy- 
droxyflavanol.37 

The  ruberythric  acid  of  madder  root  gives  alizarine  and  2  mole- 
cules of  glucose  when  boiled  with  dilute  acids.38 

329.  Salicine  heated  to  80°  with  10  parts  of  fuming  hydrochloric 
acid    (d.    1.25),    gives    2    molecules    of    glucose39    and    saliretine, 
0(C6H4.CH2  .OH) 2,  while  the  action  of  emulsine  in  the  cold  or 
boiling  with  dilute  acid  leads  to  saligenine,  o.HO  .  C6H4 .  CH2OH.40 

Amygdaline  is  decomposed  by  boiling  with  dilute  hydrochloric 
or  sulphuric  acid,  just  as  it  is  in  the  cold  by  emulsine,  into  benzalde- 
hyde,  hydrocyanic  acid,  and  2  molecules  of  glucose: 

C^H^NOn  +  2H20  =  C6H5 .  CHO  +  HCN  +  2C6H1206. 

But  when  acids  are  used  the  hydrocyanic  acid  formed  is  rapidly 
hydrolyzed  into  formic  acid  and  ammonia.41 

Conijerine  is  split  by  emulsine  into  glucose  and  contferyl  alcohol, 
but  when  the  hydrolysis  is  carried  out  by  boiling  with  dilute  acids, 
the  alcohol  is  resinified.42 

35  KAWALEHR,  Annalen,  84,  356  (1852). 

as  PIRIA,  Annalen,  56,  64  (1845). 

37  RIGAUD,  Annalen,  90,  289  (1856). 

38  GRAEBB  and  LIEBERMANN,  Annalen,  SupL,  7,  296  (1870). 

39  KRAUT,  Annalen,  156,  124  (1870). 

40  PIRIA,  Annalen,  56,  37  (1845). 

41  LUDWIG,  Jahresber.,  1855,  699  and  1856,  679,  Arch.  Pharm.  (2),  87,  273. 

42  TIEMANN  and  HAARMANN,  Berichte,  7,  611  (1874). 


121  HYDRATIONS  334 

330.  The  dilute  acids  can  be  replaced  by  dilute  soluble  bases  such 
as  sodium,  potassium  and  barium  hydroxides  or  even  by  a  solution 
of  zinc  chloride  (for  example  with  helleborine)  ,43 

331.  Acidamides  and  Analogous  Compounds.    The  derivatives 
formed  by  the  loss  of  a  molecule  of  water  between  an  organic  acid 
and  ammonia,  an  amine,  hydroxylamine,  hydrazine,  phenylhydrazine 
or  semicarbazid  can  be  more  or  less  readily  hydrolyzed  into  the  mole- 
cules from  which  they  were  derived.     This  hydrolysis  can  be  accom- 
plished by  mineral  acids  which  combine  with  the  ammonia  or  other 
base  or  by  aqueous  alkalies  which  unite  with  the  organic  acid. 

Amides  which  can  be  hydrolyzed  by  boiling  with  pure  water  are 
much  more  rapidly  hydrolyzed  by  heating  with  dilute  mineral  acids 
or  with  dilute  alkalies. 

332.  The  hydrolysis  of  oximes  takes  place  on  contact  with  hot 
concentrated  hydrochloric  acid,  which  combines  with  the  hydroxyl- 
amine that  is  liberated  along  with  the  aldehyde  or  ketone. 

Phenylhydrazones  are  hydrolyzed  in  the  cold  with  concentrated 
hydrochloric  acid  which  combines  with  the  phenylhydrazine. 

^N N<v 

Bisdiazoacetic  acid,HOOC .<j(  ;C .  COOH, is  hydrolyzed 

\NH-NH/ 

by  sulphuric  acid  diluted  with  4  molecules  of  water  to  give  2  mole- 
cules of  hydrazine  and  2  molecules  of  oxalic  acid.44 

333.  Heating  in  a  sealed  tube  with  a  concentrated  solution  of 
hydrochloric  acid  causes  the  hydrolysis  of  sulphocyanic  esters: 

CN  .  SR  +  2H20  =  R  .  SH  +  C02  +  NH3, 
as  well  as  of  mustard  oils,  or  isosulphocyanic  esters: 

CS  :  NR  +  2H2O  =  H2S  +  C02  +  H2NR. 

amine 

334.  On  the  contrary,  the  hydrolysis  of  isocyanic  esters,  or  alkyl 
carbylamines,  is  carried  out  by  boiling  with  aqueous 45  or  alcoholic 46 
potash : 

CO  :  NR  +  H20  =  C02  +  H2NR, 

and  the  activity  of  the  base  can  be  attributed  to  its  affinity  for  car- 
bonic acid. 

43  HUSEMANN  and  MARME,  Annalen,  135,  55  (1865). 

44  CURTIUS  and  LANG,  J.  prakt.  Chem.  (2),  38,  532  (1888). 

45  WURTZ,  Ann.  Chim.  Phys.  (3),  42,  43  (1854). 

46  HALLER,  Bull.  Soc.  Chim.  (2),  45,  706  (1886). 


335  CATALYSIS  IN  ORGANIC  CHEMISTRY  122 

335.  The  hydrolysis  of  amides  and  of  alky  I  amides  can  be  carried 
out  by  acids  or  alkalies  indifferently.     In  the  case  of  aliphatic  amides, 
the  reaction  is  usually  effected  by  heating  with  alcoholic  potash  or 
soda  and  takes  place  slowly,  sometimes  requiring  heating  for  several 
days.    We  have: 

R  .  CO  .  NH2  +  H20  =  R  .  C02H  +  NH3, 

and  we  may  believe  that  the  affinity  of  the  potash  for  the  acid  deter- 
mines the  reaction. 

336.  In  most  of  the  above  reactions  the  catalytic  role  of  the  acids 
and  bases  does  not  appear,  at  first  sight,  to  be  well  established.    We 
can,  however,  assume  that  it  is  really  catalytic,  since  in  the  reactions 
that  have  been  most  closely  studied,  such  as  the  hydrolysis  of  amides, 
amounts  of  acid  far  less  than  equivalent  to  the  amides  greatly  accel- 
erate the  reaction.    In  the  case  of  the  hydrolysis  of  acetamide  by 
dilute  mineral  acids,  it  has  been  found  that  the  activity  of  the  acids 
is  proportional  to  their  ionization  and  to  the  concentration  of  the  ions 
in  the  system.47 

§  2.  —  HYDROLYSIS    IN    GASEOUS    SYSTEMS 

337.  The  Saponification  of  Esters.     Titania,  Ti02,  which  readily 
causes  the  esterification  of  alcohols  by  aliphatic  acids  (767),  between 
280  and  300°,  just  as  readily  reverses  the  reaction  and  brings  about 
the  saponification  of  esters  by  water.    The  rapid  passage  of  a  mix- 
ture of  water  and  ester  vapors  in  equivalent  amounts  over  the  oxide 
at  280  to  300°  is  sufficient  to  reach  about  30%  hydrolysis  and  this 
percentage  is  increased  as  the  relative  amount  of  water  is  increased 
till  practically  complete  hydrolysis  is  effected  by  very  large  amounts 
of  water.  " 

Thoria  can  produce  the  same  effect  but  with  less  activity.48 

338.  Ethers.    Thoria,  Th02,  which  effectively  catalyzes  the  forma- 
tion of  phenyl  oxide,   (C6H5)2O,  from  phenol  at  400  to  500°,  can 
equally  well  decompose  it  when  phenyl  ether  and  water  vapor  are 
passed  over  the  heated  oxide,  the  decomposition  reaching  50%.  49 

339.  Hydrolysis  of  Carbon  Bisulphide.     The  reaction  of  water 
vapor  on  carbon  disulphide  in  the  presence  of  appropriate  catalysts, 
such  as  ferric  oxide,  can  be  considered  a  case  of  hydrolysis.    The  re- 
action is  incomplete  but  goes  in  this  direction: 

CS       2H0  =  C02  +  2H2S. 


47  OSTWALD,  /.  prakt.  Chem.  (2),  27,  1  (1883). 

48  SABATIER  and  MAILHE,  Compt.  rend.,  152,  494  (1911). 

49  SABATIER  and  ESPIL,  Butt.  Soc.  Chim.  (4),  15,  228  (1914). 


123  HYDRATIONS  341 

This  reaction  applied  to  illuminating  gas  suppresses  67%  of  the 
carbon  disulphide  which  it  contains  and,  if  the  hydrogen  sulphide  is 
absorbed  as  rapidly  as  it  is  formed,  all  of  the  carbon  disulphide  is 
eliminated.50 

III.  —  ALCOHOLYSIS 

340.  The  action  of  alcohols  on  esters  can  be  compared  to  the  sapon- 
ification  of  esters  by  water  and  is  likewise  catalyzed  by  small  quanti- 
ties of  strong  mineral  acids,  hydrochloric  and  sulphuric.61 

If  a  primary  aliphatic  alcohol,  R'OH,  is  mixed  with  the  ester  de-. 
rived  from  an  acid,  RCOOH  and  a  complex  alcohol,  MOH,  we  shall 
have:  52 

R  .  CO  .  OM  +  R' .  OH  =  MOH  +  R  .  CO  .  OR'. 

The  alcohol,  MOH,  is  set  free.  This  is  what  takes  place  when 
methyl,  ethyl,  propyl  alcohols  and  the  like  attack  the  esters  of  borneol, 
glycerine,  etc.,  in  the  presence  of  a  minute  amount  of  hydrochloric 
acid. 

Thus  bornyl  acetate  in  a  methyl  alcohol  solution,  containing  1% 
hydrochloric  acid,  is  rapidly  decomposed  into  borneol  and  methyl 
acetate. 

Glycerides  dissolved  in  absolute  alcohol  containing  a  few  per  cent 
of  hydrogen  chloride  yield  glycerine  and  the  fatty  acid  ethyl  esters.58 

341.  Haller  has  designated  these  saponifications  which  take  place 
readily  with  all  the  fats,  by  the  name  of  alcoholysis.    They  can  be 
carried  out  by  mixing  100  g.  of  a  fat  with  200  g.  dry  methyl  alcohol 
containing  1  or  2  g.  hydrogen  chloride  and  heating  on  a  steam  bath 
under  reflux  till  the  mixture  becomes  homogeneous.    If  necessary 

50  GRILLET,  Soc.  Tech.  de  Ulnd.  du  gaz  en  France,  1918,  245. 

51  Sodium  alooholate  is  an  even  better  catalyst  than  hydrochloric  acid.    In 
the  transformation  of  methyl  benzoate  into  the  ethyl  ester,  sodium  ethylate 
was  found  to  be  about  4,000  times  as  efficient  as  an  equivalent  amount  of 
hydrochloric  acid.     (REID,  Amer.  Chem.  J.,  45,  506  (1911)  ).  — E.  E.  R. 

52  This  reaction  is  a  perfectly  general  one  and  simple  alcohols  may  be  re- 
placed as  well  as  "  complex,"  thus  methyl  alcohol  replaces  ethyl  and  vice  versa 
as  shown  by  REID  (Amer.  Chem.  J.,  45,  479  (1911)  ),  and  recently  by  REIMEB 
and  DOWNES  (J.  Amer.  Chem.  Soc.,  43,  945  (1921)  ). 

For  a  number  of  references  on  alcoholysis  see  article  by  PARDEE  and  REID 
(/.  Ind.  and  Eng.  Chem.,  12,  129  (1920)  ).  It  is  a  reversible  reaction,  the 
equilibrium  point  depending  on  the  concentrations  and  activities  of  the  two 
alcohols  competing  for  the  acid  and  hence  can  never  be  complete,  no  matter 
how  much  one  alcohol  predominates.  —  E.  E.  R. 

63  ROCHLEDER,  Annalen,  59,  260  (1846).  BERTHELOT,  Ann.  Chim.  Phys.  (3), 
41,  311  (1854). 


341  CATALYSIS  IN  ORGANIC  CHEMISTRY  124 

more  hydrogen  chloride  may  be  added  during  the  reaction.  The  mix- 
ture is  finally  poured  into  brine  which  dissolves  the  glycerine  and 
causes  the  methyl  esters  of  the  fatty  acids  to  separate  as  a  top  layer.5* 
This  reaction  is  rapid  with  cocoa  butter55  and  castor  oil,  with 
which  heating  for  several  hours  is  sufficient,56  and  is  slower  with 
drying  oils  such  as  linseed.57  It  goes  just  as  well  with  ethyl,  propyl, 
and  isobutyl  alcohols.56 

54  HALLER,  Compt.  rend.,  143,  657  (1906). 

65  HALLER  and  YOUSSOUFFIAN,  Compt.  rend.,  143,  803  (1906). 

66  HALLER,  Compt.  rend.,  144,  462  (1907). 
57  HALLER,  Compt.  rend.,  146,  259   (1908). 


CHAPTER   VIII 
HYDROGENATIONS 

HYDROGEN ATIONS   IN    GASEOUS   SYSTEM, 
GENERALITIES,    USE    OF   NICKEL 

342.  Historical.     The  catalytic  properties  of  finely  divided  plati- 
num discovered  by  Davy  and  Doebereiner  at  the  beginning  of  the 
nineteenth  century,  have  shown  its  power  to  cause  oxidations.    Sev- 
eral chemists  attempted  to   apply  the  special  powers  of  platinum 
sponge  to  other  reactions  and  particularly  to  the  direct  addition  of 
hydrogen  to  various  substances.     In  1838,  Kuhlmann  showed  that 
nitric  oxide,  or  the  vapors  of  nitric  acid,  warmed  with  hydrogen  in 
the  presence  of  platinum  sponge  gave  ammonia.1     In  1852,  Coren- 
winder  observed  that  the  same  agent  caused  hydrogen  to  combine 
rapidly,  though  incompletely,  with  iodine  between  300  and  400 °.2 
In  1863,  Debus,  with  the  aid  of  platinum  black,  accomplished  the 
addition  of  hydrogen  to  hydrocyanic  acid  to  form  methyl  amine,3  and 
found  that  ethyl  nitrite  is  transformed  into  alcohol  and  ammonia 
under  the  same  circumstances.     In   1874,  von  Wilde   succeeded  in 
transforming  acetylene  into  ethylene  and  then  into  ethane,  by  plati- 
num black  at  room  temperature.4 

343.  In  a  series  of  investigations  continued  since  1897,  Sabatier 
and  Senderens  (1897-1905),  then  Sabatier  and  Mailhe  (1904-1908), 
and  Sabatier  and  Murat  (1912-1914)  have  established  and  extended 
to  a  large  number  of  cases  a  general  method  of  direct  hydrogenation 
of  volatile  organic  compounds,  based  on  the  use  of  finely  divided 
catalytic  metals  and  particularly  on  the  use  of  nickel  recently  reduced 
from  the  oxide.5 

1  KUHLMANN,  Compt.  rend.,  7,  1107  (1838). 

2  CORENWINDER,  Ann.  Chim.  Phys.  (3),  34,  77  (1852). 

3  DEBUS,  Annalen,  128,  200  (1863). 

*  VON  WILDE,  Berichte,  7,  352,   (1874). 

6  These  investigations  have  been  published  in  a  large  number  of  original 
articles  of  which  more  than  50  are  in  the  Comptes  Rendus  de  PAcademie  des 
Sciences  as  well  as  in  various  collective  memoirs  of  which  the  chief  are :  SABATIER, 
Vth  Congress  of  Pure  and  AppUed  Chemistry,  Berlin,  1904,  IV,  663.  SABATIER 
and  SENDERENS,  Confer.  Soc.  Chim.,  Paris,  1905.  SABATIER,  Rev.  Gen.  Sc.,  16, 
842  (1905).  SABATIER,  Rev.  Gle.  Chim.,  8,  381  (1905).  SABATIER  and  SENDERENS, 

125 


344  CATALYSIS  IN  ORGANIC  CHEMISTRY  126 

As  early  as  1902  this  new  method  was  taken  up  in  many  French 
and  foreign  laboratories  and  numerous  chemists  have  contributed, 
along  with  the  above  authors,  to  widen  its  application. 

344.  Essentially  the  process  consists  in  passing  the  vapors  of  the 
substance  mixed  with  hydrogen  over  a  layer  of  the  catalytic  metal, 
platinum  black,  or  even  nickel,  cobalt,  iron,  or  copper  reduced  from 
the  oxides  in  the  same  tube  in  which  the  hydrogenation  is  to  be  car- 
ried  on,    maintained    at   a    suitable   temperature,    sometimes    room 
temperature  but  more  commonly  somewhere  between  150  and  200°. 
A  temperature  around  180°  is  very  frequently  found  to  be  the  most 
suitable. 

Of  the  five  metals  mentioned  above,  nickel  is  the  most  active  and 
it  and  cobalt  are  the  only  ones  capable  of  effecting  certain  hydro- 
genations  such  as  that  of  the  benzene  nucleus.  Copper  is  less  power- 
ful and  platinum  and  iron  are  between  cobalt  and  copper. 

345.  The  apparatus  employed  by  Sabatier   and  his   co-workers 
comprises : 

1.  A  hydrogen  generator. 

2.  A  working  lube  to  contain  the  catalytic  metal. 

3.  An  arrangement  for  introducing  the  vapors  to  be  hydrogenated 
along  with  the  hydrogen. 

4.  A  receiver  to  collect  the  product  of  the  reaction. 

346.  The  Hydrogen  Generator.    The  hydrogen  can  be  prepared 
by  the  action  of  commercial  hydrochloric  acid  diluted  with  half  its 
volume  of  water  on  ordinary  granulated  zinc.    The  continuous  gen- 
erator of  Sainte-Clair  Deville  consists  of  two  large  flasks  of  10  to 
15  1.  of  which  the  lower  tubulures  are  connected  by  large  rubber  tub- 
ing.   One  flask  is  filled  with  granulated  zinc  and  the  other  with  hydro- 
chloric acid.    The  gas  is  washed  with  strong  caustic  soda  and  then 
with  concentrated  sulphuric  acid.    A  graduated  safety  tube  in  the 
acid  wash  bottle  serves  to  indicate  the  gas  pressure.    Between  the 
two  wash  bottles  is  a  stop  cock  to  regulate  the  gas  and  beyond  the 
acid  wash  bottle  is  a  pinch  cock  for  further  adjustment  of  the  pres- 
sure.   To  secure  a  regular  delivery  of  the  gas  it  is  sufficient  to  main- 
tain the  acid  in  the  safety  tube  at  a  constant  height.    On  account  of 


Ann.  Chim.  Phys.  (8),  4,  319  (1905).  SABATIER,  VI th.  Congress  Pure  and  Appl. 
Chem.,  Rome,  1906,  Xth.  Sect.  174.  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8), 
16,  70  (1909).  SABATIER,  Berichte,  44,  1984  (1911).  SABATIER,  Address  at  Stock- 
holm on  the  reception  of  the  Nobel  Prize,  Rev.  Sclent.,  i,  289  (1913).  SABATIER, 
Confer,  a  Toulouse  au  Congres  du  gaz,  Le  Gaz,  57,  1914.  SABATIER,  Confer, 
a  University  of  London,  Rev.  Gle.  Chim.,  17,  185  and  221  (1914).  SABATIER  and 
MURAT,  Ann.  de  Chim.  (9),  4,  253  (1915). 


127  HYDROGENATIONS  347 

the  large  dimensions  of  the  apparatus,  a  constant  evolution  of  gas 
can  be  maintained  for  at  least  six  hours. 

The  hydrogen  must  be  carefully  freed  from  impurities  derived 
from  the  zinc  or  from  the  acid  (hydrogen  sulphide,  arsine,  phosphine 
and  hydrochloric  acid  vapors).  For  this  purpose  it  passes  through 
a  tube  of  Jean  glass,  filled  with  copper  turnings  kept  at  a  dull  red, 
which  stops  the  major  part  of  the  impurities.  The  purification  is 
completed  by  passing  the  gas  through  a  long  tube  filled  with  slightly 
moist  fragments  of  caustic  potash  which  retains  acid  vapors  as  well  as 
any  remaining  hydrogen  sulphide.  The  purified  gas  passes  to  the 
reaction  tube. 

The  complete  drying  of  the  gas  appears  superfluous  as  it  has  been 
shown  that  moist  hydrogen  hydrogenates  benzene  or  phenol,  over 
nickel,  at  least  as  well  as  dry.6 

Electrolytic  hydrogen,  which  is  on  the  market  in  steel  cylinders 
at  high  pressures,  can  be  used  to  advantage.  These  cylinders  fitted 
with  suitable  reducing  valves,  furnish  a  nearly  pure  gas  which  can 
be  freed  from  the  small  amount  of  oxygen  which  it  contains  by  passing 
over  red  hot  copper  in  a  tube  followed  by  a  drying  tube  containing 
caustic  potash. 

347.  The  Reaction  Tube.  In  a  glass  tube  65  to  100  cm.  long 
and  14  to  18  mm.  inside  diameter,  a  longer  or  shorter  (35  to  80  cm.) 
thin  layer  of  platinum  black  or  of  the  oxide,  from  which  the  catalytic 
metal  is  to  be  prepared,  is  spread.  The  tube  is  heated  in  a  gas  fur- 
nace such  as  is  used  for  organic  combustions  but  in  which  the  burners 
have  wing  tips  with  little  holes  so  that  there  are  a  large  number  of 
little  flames  equal  in  size  and  close  together  distributing  the  heat 
evenly. 

The  tube  is  laid  in  a  semicircular  trough  and  rests  on  a  rather 
thick  layer  of  calcined  magnesia  or  fine  sand.  The  temperature  is 
taken  simply  with  a  glass  thermometer  graduated  to  450°  which  is 
embedded  in  the  trough  by  the  side  of  the  tube  and  which  may  be 
moved  from  place  to  place  to  test  the  evenness  of  the  heating. 

The  temperature  read  on  the  thermometer  is  always  a  little  lower 
than  that  in  the  tube,  the  difference  being  greater  at  higher  tempera- 
tures.7 For  temperatures  around  180  to  200°  the  difference  is  hardly 
more  than  10  to  15°,  while  at  350°  it  may  be  as  great  as 
35°.  The  limits  between  which  the  reactions  go  on  are  usually  wide 
enough  so  that  this  approximate  determination  of  the  temperature  is 
sufficient. 

6  SABATIER  and  ESPIL,  Bull.  Soc.  Chim.  (4),  15,  228  (1914). 

7  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  296  (1910). 


348  CATALYSIS  IN  ORGANIC  CHEMISTRY  128 

348.  If  more  exact  determinations  are  desired  a  rectangular  copper 
oven  12  x  15  x  65  cm.  down  the  centre  of  which  runs  a  copper  tube  is 
used.    The  thermometer  and  the  tube  containing  the  previously  pre- 
pared catalysts  are  placed  in  this  tube  side  by  side.    A  metallic  regu- 
lator contained  in  a  copper  tube  parallel  to  the  first  controls  the  gas 
and  maintains  the  temperature  at  which  it  is  set.    The  copper  box  is 
filled  with  a  liquid  which  up  to  270°  may  be  boiled  linseed  oil,  or  for 
higher  temperatures  a  mixture  of  equal  weights  of  sodium  and  potas- 
sium nitrates  which  is  liquid  above  225°.    For  delicate  hydrogena- 
tions  with  such  substances  as  benzoic  esters,  Sabatier  and  Murat 
have  employed  a  massive  bronze  block,  65  cm.  long,  10  cm.  wide  and 
7  cm.  high,  of  rectangular  cross  section,  with  rounded  corners.    Two 
symmetrically  placed  holes  25  mm.  in  diameter  run  from  one  end  to 
the  other  of  the  block:   the  one  contains  the  tube  carrying  the  nickel 
and  the  other  the  metallic  regulator  which  controls  the  gas  supply 
of  the   furnace.    Any   desired  temperature   is   thus   obtained   very 
uniformly  on  account  of  the  large  mass  of  the  good  conducting  metal. 
On  account  of  this   conductivity,  the  temperature  may   be   raised 
quickly.    Small  holes  parallel  to  the  large  ones  receive  the  thermo- 
meters. 

The  temperature  may  be  first  carried  to  350°  for  the  preparation 
of  the  nickel  and  then  lowered  to  any  desired  temperature,  such  as 
180°,  for  carrying  out  the  hydrogenation. 

In  case  nickel-coated  pumice  is  used  as  catalyst  (126)  a  very  use- 
ful arrangement  is  to  fill  the  two  limbs  of  a  vertical  U-tube  with  the 
catalyst.  This  tube  may  be  heated  in  an  air  bath  to  350°  for  reduc- 
ing the  nickel  and  then  lowered  into  an  oil  bath  kept  at  180°  or  into 
the  vapors  of  boiling  aniline,  185°,  for  the  hydrogenation. 

Heating  on  the  furnace  is  less  regular  and  requires  close  attention 
but  has  the  advantage  that  the  interior  of  the  tube  may  be  watched. 

349.  Heating  by  electric  resistance  may  be  conveniently  employed. 
The  reaction  tube  is  surrounded  by  asbestos  paper  on  which  is  wound 
a  1  mm.  ferro-nickel  spiral  which,  in  turn,  is  surrounded  by  a  second 
layer  of  asbestos  paper.    By  the  aid  of  suitable  resistances  the  current 
is  regulated  to  show  the  proper  readings  on  an  ammeter.    The  tem- 
peratures in  the  centre  of  the  tube  corresponding  to  various  ammeter 
readings  are  previously  determined  by  experiment.8 

This  method  of  heating  has  the  advantage,  as  compared  to  the 
open  furnace,  that  the  tube  is  heated  uniformly  around  its  whole 
8  The  conditions  of  the  experiment  must  be  exactly  duplicated  during  the 
calibration  since  otherwise  incorrect  estimates  of  temperatures  are  possible  as 
varying  amounts  of  heat  are  removed  by  varying  currents  of  gas  through  the 
tube.  — E.  E.  R. 


129 


HYDROGENATIONS 


351 


circumference,  and,  with  it  it  is  best  to  employ  nickeled  pumice  filling 
the  whole  tube  rather  than  a  layer  of  nickel  resting  in  the  bottom.9 

350.  Introduction  of  the  Substance.  The  method  of  introducing 
the  substance  to  be  hydrogenated  varies,  of  course,  according  to  its 
physical  state. 

If  it  is  a  gas  the  forward  end  of  the  tube  containing  the  catalyst 
carries  a  two-hole  stopper  with  two  tubes,  one  for  the  gas  and  one 
for  the  hydrogen.  The  gas  is  furnished  by  a  continuous  generator 
(as  with  acetylene  or  carbon  dioxide)  or  by  a  metal  or  glass  gasom- 
eter into  which  it  is  measured  in  advance  (carbon  monoxide,  propy- 
lene,  nitrous  oxide),  or  even  by  a  discontinuous  apparatus  which  can 
be  operated  sufficiently  regularly  (as  for  ethylene,  or  nitric  oxide). 
A  wash  cylinder  with  pressure  indicator  interposed  between  a  stop 
cock  and  a  screw  pinch  cock  as  has  been  described  above  for  hydro- 
gen (346) ,  serves  to  admit  the  gas  at  any  desired  constant  rate.  In 
the  case  of  discontinuous  generators,  a  safety  valve  is  arranged  by 
having  a  side  outlet  tube  dipping  under  mercury  so  that  the  excess  of 
gas  may  escape. 


351.  For  most  liquids,  Sabatier  and  Senderens  have  devised  an 
extremely  simple  apparatus.  The  liquid  is  conducted  by  a  capillary 
tube  to  the  interior  of  the  reaction  tube.  The  liquid  is  placed  in  a 
large  vertical  tube  T,  the  lower  end  of  which  carries  a  stopper  through 
which  passes  the  vertical  portion  of  a  bent  capillary  tube,  the  hori- 
zontal portion  of  which  passes  through  the  stopper  in  the  end  of  the 
reaction  tube. 

For  a  given  liquid,  the  flow  is  more  rapid  the  larger  the  bore  of  the 

9  BRUNEL,  Ann.  Chim.  Phys.  (8),  6,  205  (1905). 


352  CATALYSIS  IN  ORGANIC  CHEMISTRY  130 

capillary  tube  and  the  greater  the  head  of  liquid,  AB.  By  main- 
taining this  head  constant,  a  regular  flow  of  liquid  is  obtained. 

It  is  well  to  arrange  it  so  that  the  liquid  does  not  fall  from  the  end 
of  the  capillary  tube  in  drops,  but  flows  steadily  from  its  end  either 
on  to  the  wall  of  the  reaction  tube  or  over  the  surface  of  the  cork  in 
its  end. 

The  selection  of  the  capillary  tube  depends  on  the  viscosity  of  the 
liquid,  a  smaller  tube  being  used  for  mobile  liquids. 

It  is  evident  that  there  are  two  independent  ways  of  regulating 
the  flow  of  the  liquid,  by  changing  the  diameter  of  the  capillary  tube 
or  altering  its  height.  Besides,  the  capillary  tube  can  be  fed  by  a 
reservoir  with  as  large  a  surface  as  may  be  desired  and,  for  experi- 
ments of  long  duration,  the  tube  A  can  be  placed  in  communication 
with  a  flask  of  large  size  in  which  the  variations  of  level  are  very  slow. 

It  is  convenient  for  the  stopper  D  to  be  at  some  distance  from  the 
heated  portion  of  the  tube ;  3  to  4  cm.  is  sufficient.  The  layer  of  metal 
should  not  commence  for  a  little  distance,  about  10  cm.  from  the 
stopper.  The  liquid  introduced  by  the  capillary  volatilizes  regularly 
in  this  open  space.  It  is  important  to  watch  that  the  liquid  does  not 
wet  the  catalyst  which  is  frequently  altered  by  contact  with  the  liquid. 

352.  We  may  also  operate  by  bubbling  the  hydrogen  through  the 
liquid  to  be  hydrogenated,  thus  carrying  along  the  vapors.    If  the 
liquid  is  very  volatile    (acetaldehyde,  propionic  aldehyde,  nitrogen 
peroxide,  etc.)  cooling  is  necessary  so  that  the  amount  of  the  vapors 
carried  along  will  not  be  too  great. 

If  the  liquid  is  only  slightly  volatile,  heating  may  be  required, 
always  selecting  a  temperature  so  that  the  hydrogen  will  be  in  excess 
of  that  required  for  complete  hydrogenation.9* 

353.  For  solid  substances  which  melt  below  100°,  the  same  appa- 

9a  In  order  to  get  an  equimolecular  mixture  of  the  vapor  and  hydrogen, 
the  liquid  through  which  the  hydrogen  is  bubbled  must  be  kept  at  such  a  tem- 
perature that  its  vapor  pressure  is  380  mm.  For  some  liquids  this  temperature 
may  be  found  from  tables  in  the  literature.  The  vapor  pressure  curves  for 
various  classes  of  liquids  are  not  quite  similar,  owing  to  different  degrees  of 
association,  but  for  most  organic  liquids,  except  the  lower  alcohols,  the  vapor 
pressure  is  380  mm.  at  from  20  to  24°  below  their  boiling  points.  To  have  a 
little  more  than  1  molecule  of  hydrogen  to  1  of  the  vapor  the  liquid  should  be 
kept  at  from  25  to  30°  below  its  boiling  point.  These  same  liquids  have  vapor 
pressures  approximately  one  third  of  an  atmosphere  at  32  to  36°  below  their 
boiling  points  and  should  be  kept  at  such  temperatures  to  obtain  2  molecules 
of  hydrogen  to  1  of  the  vapor  or  at  somewhat  lower  temperatures  if  an  excess 
of  hydrogen  is  desired,  as  is  usually  the  case.  Similar  calculations  may  be. made 
when  a  larger  number  of  molecules  of  hydrogen  to  one  of  the  compound  are 
desired.  —  E.  E.  R. 


131  HYDROGENATIONS       .  357 

ratus  may  be  used  by  surrounding  the  capillary  tube  and  the  vertical 
tube  T  with  a  sort  of  cylindrical  air  bath,  the  lower  end  of  which  is 
heated  by  a  Bunsen  burner.  The  current  of  warm  air  is  sufficient  to 
maintain  the  substance  in  the  liquid  condition.  This  method  may 
be  used  with  phenol,  the  cresoles,  the  nitronaphthalines  and  naphtha- 
line. 

A  thick  copper  capillary  tube  brazed  on  to  a  copper  vertical  tube  T 
may  be  used,  and  this  may  be  heated  directly  by  a  small  flame. 

When  the  substance  melts  above  100°,  it  is  placed  in  long  porcelain 
boats  in  the  forward  part  of  the  tube,  a  long  tube  being  selected.  The 
volatilization  of  the  substance  is  effected  by  careful  heating,  a  portion 
at  a  time,  starting  from  the  end  next  to  the  heated  metal.  The  re- 
action is  of  course  limited  to  the  amount  of  material  in  the  boats  and 
is  consequently  intermittent. 

Solids  melting  below  180°  may  be  kept  fused  by  a  suitable  air  bath 
and  the  vapors  carried  on  by  the  hydrogen  which  is  bubbled  through. 

354.  When  the  product  of  the  hydrogenation  is  a  liquid,  it  is  fre- 
quently sufficient  to  mix  some  of  it  with  the  solid  to  be  hydrogenated, 
thus  lowering  the  melting  point  so  that  the  usual  apparatus  for  liquids 
may  be  employed.    This  is  the  case  with  phenol  and  with  ortho  and 
meta  cresoles. 

The  use  of  solvents  which  can  not  be  hydrogenated,  such  as  water, 
paraffine  hydrocarbons  (hexane,  heptane,  etc.)  usually  gives  poor 
results,  particularly  when  water  is  used. 

355.  Apparatus  for  Collecting  the  Reaction  Products.    If  the 
products  of  the  hydrogenation  are  all  gases,  they  are  collected  at  the 
end  of  the  catalyst  tube  in  a  gas  holder  over  water,  care  being  taken 
to  saturate  the  water  with  common  salt  to  diminish  the  solubility  of 
the  gases.    It  is  well  to  time  the  collection  of  issuing  gas  in  a  gradu- 
ated tube.    A  comparison  of  the  rate  at  which  the  gases  come  out 
with  the  rate  at  which  they  are  passed  in,  frequently  gives  valuable 
information  as  to  the  exact  course  of  the  reaction. 

356.  If  the  products  are  partly  or  entirely  liquid,  the  reaction  tube 
is  connected  with  a  condenser.    When  the  substances  are  only  slightly 
volatile  this  may  be  simply  a  double-necked  flask.    When  the  vola- 
tility, at  room  temperature,  is  considerable,  a  U-tube  is  employed 
from  the  bottom  of  which  a  tube  leads  down  into  a  flask  in  which  the 
liquid  collects.    The  U-tube  is  placed  in  an  inverted  tubulated  bell- 
jar  which  is  filled  with  cold  water,  ice,  or  a  freezing  mixture.    The 
gas  issuing  from  the  other  limb  of  the  U-tube  is  collected  over  water 
and  measured. 

357.  Solid  reaction  products  are  collected  by  prolonging  the  re- 


358  CATALYSIS  IN  ORGANIC  CHEMISTRY  132 

action  tube  and  cooling  the  further  end.  The  tube  should  be  long 
enough  to  project  a  considerable  distance  from  the  furnace  and  the 
end  should  be  inclined  downward  so  that  condensed  liquids  will  not 
run  back  towards  the  catalyst. 


HYDROGENATIONS    BY    MEANS    OF    NICKEL 

358.  In  Chapter  II  the  conditions  have  been  described  under  which 
nickel  may  be  used  to  advantage  as  a  catalyst  for  hydrogenations 
(53) ,  and  methods  have  been  given  for  obtaining  a  metal  of  excellent 
catalytic  properties.     Nickel  reduced  at  a  red  heat  below  700°  is 
capable  of  effecting  all  sorts  of  hydrogenations  and  in  particular 
can  hydrogenate  benzene  to  cyclohexane ; 10  but  that  reduced  above 
750°,  or  which  has  been  heated  to  that  temperature  after  having  been 
reduced  at  a  lower,  is  incapable  of  hydrogenating  benzene,  is  no  longer 
pyrophoric  and  does  not  gain  in  weight  when  exposed  to  cold  air. 
It  is  then  capable  of  only  certain  hydrogenations,  such  as  the  reduc- 
tion of  nitro  derivatives.  «| 

359.  As  has  been  stated  above   (112),  the  presence  of  chlorine, 
bromine,  or  iodine,  even  in  traces,  in  the  metal  paralyzes  its  catalytic 
activity.    An  oxide  prepared  by  precipitation  from  the  chloride  can 
not  be  used,  but  good  results  can  be  obtained  with  an  oxide  produced 
by  calcining  the  sulphate  at  a  red  heat. 

Whatever  care  one  may  take,  it  is  never  possible  to  avoid  all  the 
causes  of  poisoning  the  metal  catalyst  and  particularly  in  consequence 
of  the  progressive  fouling  of  the  metal  which  is  more  or  less  rapid  ac- 
cording to  the  work  done  with  it,  a  gradual  diminution  of  the  catalytic 
power,  its  senilescence,  so  to  speak,  is  noticed. 

360.  Darzens  believes  that  nickel  exists  in  three  forms,  a,  ft,  and  7. 
The  very  active  7  form  is  said  to  be  obtained  by  reduction  below  260° 
and  is  considered  unstable,  remaining  in  metastable  state  below  260°. 
Above  that  temperature  it  passes  into  the  less  active  ft  nickel,  then 
at  a  bright  red  into  the  a  form  which  is  entirely  inactive  for  hydro- 
genations.11   According  to  this  author  the  power  to  hydrogenate  ben- 
zene belongs  exclusively  to  y  nickel,  which  is  contrary  to  the  observa- 
tions of  Sabatier  and  Espil  quoted  above.    These  transformations  of 
7  nickel,  rapid  at  high  temperatures,  would  take  place  slowly  even 
at  low  temperatures  and  would  explain  the  senilescence  of  the  metal 
apart  from  many  poisoning  effects.12 

10  SABATIER  and  ESPIL,  Bull.  Soc.  Chim.  (4),  15,  779  (1914). 

11  DARZENS,  Bull.  Soc.  CMm.  (4),  15,  771  (1914). 

12  DARZENS,  Compt.  rend.,  139,  869  (1904). 


133  HYDROGENATIONS  364 

361.  Choice  of  Reaction  Temperature.    A  given  hydro  genation 
can  be  realized  only  within  a  well-defined  temperature  interval. 

In  practice,  a  lower  temperature  limit  is  set  by  the  necessity  of 
maintaining  in  the  vapor  state  in  the  reaction  tube,  not  only  the  com- 
pounds to  be  transformed  but  also  the  products  of  the  reaction. 

To  a  certain  extent  elevation  of  temperature  accelerates  the  re- 
action and  consequently  raises  the  proportion  of  the  substance  hydro- 
genated  during  its  passage  through  the  tube.  But  beyond  a  certain 
limit,  sometimes  not  far  above  the  temperature  at  which  the  reaction 
begins,  there  is  a  profound  modification  of  the  phenomenon,  it  being 
possible  to  completely  reverse  the  reaction  in  some  cases.  Thus  the 
hydrogenation  of  benzene  may  be  accomplished  as  low  as  70°,  and 
it  increases  in  velocity  as  the  temperature  is  raised  till  a  maximum  is 
reached  at  180-200°.  Then  it  decreases  till  300°  is  reached,  at  which 
benzene  is  no  longer  hydrogenated,  but,  on  the  contrary,  cyclohexane 
is  decomposed  into  benzene  and  hydrogen. 

362.  By  hydrogenating  around  300°,  the  aromatic  nucleus  remains 
almost   unaffected    while  any    unsaturated    side-chains    are    hydro- 
genated.13   Thus  styrene,  C6H5CH  :  CH2,  hydrogenates  almost  com- 
pletely at  300°  to  ethyl-benzene,  C6H5.CH2.CH3,  while  if  the  tem- 
perature be  reduced  to   180°,  this  is   further   changed   into   ethyl- 
cyclohexane,  CeH^.CH^CHg. 

If  the  temperature  is  raised  above  300°,  the  aromatic  nucleus  is, 
little  by  little,  broken  up,  and  particularly  in  the  case  of  benzene  the 
reaction  : 


methane 

tends  to  become  more  and  more  important.14 

363.  When  a  compound  can  add  several  molecules  of  hydrogen  in 
succession,  we  can  sometimes  contrive,  by  suitably  choosing  the  tem- 
peratures, to  produce  one  after  the  other  of  the  various  combina- 
tions.15    In  the  hydrogenation  of  anthracene  over  nickel,  at  180°, 
perhydro-anthracene,   C14H24,   is   obtained   along  with  the   dodeca- 
hydro-,    at    200°,    the    octohydro-,    and    at    260°,    the    tetahydro- 
anthracene.16 

364.  The  easy  hydrogenations  are  those  which  take  place  over  a 
wide  range  of  temperatures,  as  the  saturation  of  ethylene  bonds  or 
the  reduction  of  nitro  compounds.    The  more  difficult  cases  are  those 

13  SABATIER  and  MURAT,  Ann.  de  Chim.  (9),  4,  255  (1915). 

14  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  334  (1905). 

15  SABATIER  and  MAILHE,  Compt.  rend.,  137,  240  (1903). 

16  GODCHOT,  Ann.  Chim.  Phys.  (8),  12,  468  (1907). 


365  CATALYSIS  IN  ORGANIC  CHEMISTRY  134 

where  the  possible  temperature  interval  is  narrow,  as  is  the  case  in 
the  hydrogenation  of  the  aromatic  nucleus,  especially  with  diphenols, 
pyrogallol,17  benzoic  esters,  and  quinoline.18 

365.  As  has  been  stated  above  (167),  the  hydrogenating  activity  of 
nickel  is  attributed  to  the  rapid  formation  of   a  hydride   formed 
directly  by  the  hydrogen  gas  on  the  surface  of  the  metal.     This 
hydride  is  readily  dissociated,  and  if  it  is  brought  into  contact  with 
substances  capable  of  taking  up  hydrogen,  it  gives  it  to  them  very 
rapidly,  regenerating  the  metal  which  can  again  form  the  hydride, 
repeating  these  reactions  indefinitely. 

The  well-attested  impossibility  of  carrying  on  all  sorts  of  hydro- 
genations  with  any  sort  of  nickel  leads  to  the  idea  that  there  are 
several  stages  of  combination  with  hydrogen.  The  nickel  produced 
above  700°  can  doubtless  form  only  the  first  hydride,  comparable  to 
that  formed  by  copper,  and  capable  of  reacting  with  nitro  groups  or 
with  an  ethylene  hydrocarbon.  Only  powerful  nickel,  such  as  is 
furnished  by  the  reduction  at  a  low  temperature  of  the  oxide  pre- 
pared from  the  nitrate,  can  form  a  perhydride  capable  of  hydro- 
generating  the  aromatic  nucleus  (167). 

RESULTS  OBTAINED  BY  HYDROGENATION  OVER 
NICKEL  IN  GASEOUS  SYSTEM 

366.  The  results  obtained  by  hydrogenation  over  reduced  nickel 
can  be  divided  into  four  groups: 

1.  Simple  reductions  without  fixation  of  hydrogen, 

2.  Reductions  with  simultaneous  fixation  of  hydrogen, 

3.  Addition  of  hydrogen  to  molecules  which  contain  multiple  bonds 
between  various  atoms, 

4.  Hydrogenations     accompanied     by     decomposition     of     the 
molecule. 

REDUCTIONS    EFFECTED    WITHOUT    FIXATION 
OF  HYDROGEN 

367.  The  reduction  effected  by  the  aid  of  nickel  corresponds  most 
frequently  to  the  elimination  of  oxygen  in  the  form  of  water;  it  can 
also  remove  sulphur  as  hydrogen  sulphide. 

368.  Nitrous  Oxide.    The  first  case  is  furnished  by  nitrous  oxide 
which  is  reduced  to  nitrogen,  even  at  the  ordinary  temperature,  with- 

"  SABATIER,  Berichte,  44,  1997  (1911). 

18  SABATIEB  and  MURAT,  Compt.  rend.,  158,  309  (1914). 


135  HYDROGENATIONS  370 

out  any  production  of  ammonia  or  hydrazine.  By  increasing  the 
proportion  of  nitrous  oxide  in  the  hydrogen,  the  heat  evolved  raises 
the  first  portions  of  the  nickel  to  incandescence,  and  there  results  a 
partial  decomposition  of  the  nitrous  oxide  with  the  appearance  of  red 
nitrogen  peroxide,  the  hydrogenation  of  which  carried  on  by  the 
neighboring  hot  nickel  gives  a  little  ammonia.19 

369.  Aromatic   Alcohols.     The   hydrogenation  of   aromatic   al- 
cohols over  nickel  at  350-400°  replaces  the  hydroxyl  group  by  hydro- 
gen and  leads  to  the  corresponding  aromatic  hydrocarbon.20 

Benzyl  alcohol  is  changed  to  toluene,  phenylethyl  alcohol  to  ethyl- 
benzene,  benzhydrol,  C6H5.CH(OH).C6H6,  is  changed  quantitatively 
into  diphenyl-methane,  C6H5.CH2.C6H5,  and  phenyl-p.cresyl  carbinol, 
into  phenyl-p.cresyl-methane. 

Likewise,  vapors  of  triphenyl  carbinol,  carried  along  by  benzene 
vapors  and  hydrogen  over  nickej  at  400°,  readily  yield  triphenyl- 
methane. 

This  reaction  is  particularly  easy  when  the  alcoholic  hydroxyl  is 
attached  to  a  carbon  atom  adjoining  a  carbon  atom  united  to  hydro- 
gen in  the  same  paraffme  side-chain.  The  mechanism  of  the  reaction 
may  then  correspond  to  a  dehydration  into  the  phenyl-ethylene 
hydrocarbon,  which  is  at  once  hydrogenated  into  the  saturated  hydro- 
carbon. Thus  tolyl-dimethyl  carbinol,  CH3.C6H4.C(OH).(CH3)2, 
which  is  very  readily  dehydrated,  gives  with  a  nickel  only  slightly 
active  cymene,  which  may  be  transformed  into  menthane  if  an  active 
nickel  is  used  below  ISO0.21 

370.  Phenols    and    Polyphenols    above    250°.    Phenol    hydro- 
genated at  250  to  300°  over  nickel,  gives  only  benzene  with  the  elimi- 
nation of  water: 

C6H5.OH  +  H2  =  H20  +  C6H6. 

But  the  reaction  is  slow  and  much  of  the  phenol  passes  by 
unchanged.  If  the  attempt  is  made  to  hasten  the  reaction  by 
raising  the  temperature,  the  benzene  is  attacked  with  the  formation 
of  methane.  The  three  cresoles  behave  the  same  way  and  yield 
toluene. 

At  250°  the  diphenols  (pyrocatechin,  resorcine,  and  hydroquinone) 
undergo  a  similar  reaction,  the  hydroxyl  groups  being  successively  re- 
placed by  hydrogen,  phenol  being  first  formed  and  then  benzene.22 

19  SABATIER  and  SENDERENS,  Compt.  rend.,  135,  278  (1902). 

20  SABATIER  and  MURAT,  Ann.  de  Chim.  (9),  4,  258  (1915). 

21  SMIRNOF,  J.  Russian  Phys.  Chem.  Soc.,  41,  1374  (1909). 

22  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  429  (1905). 


371  CATALYSIS  IN  ORGANIC  CHEMISTRY  136 

371.  Furfuryl   Alcohol.     This   alcohol   submitted  to   a   careful 
hydrogenation  over  nickel  at  190°,  yields  methylfurjurane.23 

CH-CH  CH-CH 


H    C.CH2OH    -»    CH    C.CH3 

\  /  \  / 

O  O 

372.  Carbon  Bisulphide.    Carbon  disulphide  submitted  to  hydro- 
genation over  nickel  below  200°,  gives  an  addition  product  having  a 
very  disagreeable  odor   (492),  but  if  the  operation  is  carried  on  at 
450-500°,  in  excess  of  hydrogen,  the  reaction  takes  place  thus: 

CS2  +  2H2  =  2H2S  +  C. 

This  reaction  is  utilized  in  freeing  coal  gas  from  carbon  disulphide 
which  it  contains  up  to  0.02%. 

The  gas  is  freed  from  hydrogen  sulphide  by  chemical  purification 
in  the  Laming  absorbers  and  is  then  heated  to  400°  and  passed 
through  steel  tubes  7  cm.  in  diameter  containing  porous  earth  im- 
pregnated with  nickel  and  heated  to  between  400  and  500°.  The  gas 
is  cooled  when  it  passes  out  of  the  tubes  and  is  freed  by  a  second 
passage  through  the  chemical  absorbers  from  the  hydrogen  sulphide 
which  has  been  formed.  On  account  of  the  deposition  of  carbon  and 
also  on  account  of  a  certain  sulphurization  of  the  surface,  the  nickel 
loses  its  activity  rather  rapidly.  It  is  regenerated  by  passing  air 
which  burns  up  the  carbon  and  converts  the  nickel  to  the  oxide  which 
is  again  reduced  by  the  first  portions  of  gas  that  enter.  The  installa- 
tion of  this  process  at  the  Greenwich  gas  works  is  capable  of  handling 
500,000  cu.  m.  per  day.24 

REDUCTIONS    WITH    SIMULTANEOUS    FIXATION 
OF  HYDROGEN 

373.  These  reductions  can  be  considered  as  true  substitutions  of 
hydrogen  either  for  oxygen  or,  in  a  few  cases,  for  the  halogens, 
chlorine  or  bromine. 

374.  Oxides  of  Nitrogen.    Although  the  oxides  of  nitrogen  are 
outside  of  the  scope  of  this  treatise,  yet  their  close  connection  with 
organic  nitro  and  nitroso  compounds  justifies  us  in  mentioning  the 
conditions  of  their  catalytic  hydrogenation. 

23  PADOA  and  PONTI,  Lincei,  15  (2),  610  (1909);  C.,  1907  (1),  570. 

24  CARPENTER,  J.  Gas  Lighting,  126,  928  (1914).    EVANS,  /.  Soc.  Chem.  Ind., 
34,  9  (1915). 


137  HYDROGENATIONS  377 

Nitric  oxide,  NO,  is  readily  reduced  above  180°  with  the  forma- 
tion of  ammonia  and  water  according  to  the  equation: 

NO  +  5H  =  NH3  +  H20. 

But  the  nitric  oxide  reacts  with  the  ammonia  more  and  more 
rapidly  the  highjer  the  temperature,  giving  nitrogen  and  water  ac- 
cording to  the  equation: 

2NH3  +  3NO  =  5N  +  3H20. 

By  progressively  increasing  the  proportion  of  nitric  oxide,  the 
metal  becomes  incandescent  and  this  greatly  increases  the  produc- 
tion of  nitrogen.25 

375.  If  hydrogen  which  has  passed  through  a  thin  layer  of  liquid 
nitrogen  peroxide,  cooled  a  little  below  0°,  is  passed  over  cold  reduced 
nickel,  a  slight  evolution  of  heat  is  noticed  which  is  due  to  the 
formation  of  nickel  nitride.26 

If  it  is  heated  to  180°,  white  fumes  of  ammonium  nitrate  and 
nitrite  appear  which,  when  hydrogenated  further,  give  ammonia  and 
water.  We  have  finally: 

N02  +  7H  =  NH3  +  2H20. 

If  the  proportion  of  nitrogen  peroxide  in  the  hydrogen  is  increased 
by  warming  the  vessel  containing  the  nitrogen  peroxide,  the  white 
fumes  are  produced  in  abundance  and  incandescence  of  the  nearest 
portion  of  the  metal  layer  is  noticed  and  a  violent  explosion  soon 
takes  place.25 

376.  The  vapors  of  nitric  acid  mixed  with  hydrogen  and  passed 
over  nickel  at  290°  give  much  ammonium  nitrate.    At  350°  only 
water,  ammonia,  and  free  nitrogen  are  produced.26 

377.  Aliphatic  Nitro  Compounds.    Nitromethane  is  completely 
hydrogenated  between  150  and  180°  to  methyl-amine  without  any 
side  reactions.    But  above  200°  and  particularly  towards  300°,  there 
is  partial   hydrogenation   of  the  methyl-amine   into  methane   and 
ammonia:27 


CH3  .  N02  +  4H2  =  CH4  +  NH3  +  2H20 

and  at  the  same  time,  the  formation  of  certain  amounts  of  dimethyl- 
and  trimethyl-amines  along  with  the  ammonia  by  a  reaction  identical 
with  that  which  has  been  described  in  the  hydrogenation  of  nitriles. 

25  SABATIEK  and  SENDERENS,  Compt.  rend.,  135,  278  (1902). 

26  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (7),  7,  413  (1895). 

27  SABATIER  and  SENDERENS,  Compt.  rend.,  135,  226  (1902). 


378  CATALYSIS  IN  ORGANIC  CHEMISTRY  138 

Likewise  nitroethane  is  readily  transformed  at  200°  into  ethyl- 
amine  accompanied  by  diethyl-amine,  triethyl-amine  and  ammonia. 
At  350°  the  matter  is  complicated  by  the  formation  of  ethane  and  also 
of  methane  which  is  due  to  the  dissociation  of  the  ethane  by  the 
nickel.  But  this  secondary  formation  of  the  hydrocarbon  is  less 
than  with  nitromethane. 

378.  Aromatic  Nitro  Compounds.    Above  200°  nitrobenzene  is 
rapidly  transformed  into  aniline,  but  the  aniline  is  immediately  hydro- 
genated  to  form  cyclohexylamine,  etc.  (466) .     If  only  slightly  active 
nickel  is  used,  the  nucleus  is  not  hydrogenated  and  aniline  is  the  only 
product.28 

Above  250°,  a  part  of  the  nitrobenzene  is  reduced  to  benzene  and 
ammonia : 

C6H5 .  N02  +  4H2  -  C6H6  +  NH3  +  2H20. 

This  reaction  is  more  in  evidence  above  300°  and  even  the  benzene 
is  broken  up  to  form  methane: 

C6H5 .  N02  +  13H2  =  6CH4  +  NH3  +  2H20. 

Ortho  and  meta  nitrotoluenes  behave  similarly  with  a  nickel  cat- 
alyst at  200  to  250°,  and  as  the  further  hydro genation  of  the  resulting 
toluidines  does  not  take  place  readily,  the  toluidines  are  obtained 
nearly  pure. 

These  reactions  can  be  used  in  the  factory  and  it  has  been  pro- 
posed to  prepare  aniline  by  passing  a  current  of  hydrogen  and  steam 
through  nitrobenzene  maintained  at  120°  and  then  into  a  long  tube 
containing  reduced  nickel  also  kept  at  120°.  A  theoretical  yield  is 
claimed.29 

379.  a-Nitronaphthalene  gives  at  300°  beautiful  white  needles  of 
a-naphthyl  amine,  but  if  the  temperature  is  raised  to  330°,  or  better, 
to  380°,  ammonia  is  evolved  and  there  condense,   along  with  the 
diminishing   naphthyl   amine,   naphthalene    and    tetrahydronaphtha- 
lene.28    We  have: 

C10H7 .  N02  +  4H2  =  C10H8  +  NH3  +  2H20. 

380.  Dinitro  derivatives  are  transformed  with  the  same  facility. 
The  dinitrobenzenes  give  the  corresponding  diamines  at  190-210°. 
At  250°,  there  is  the  splitting  off  of  ammonia  to  form  aniline.30    Like- 

28  SABATIEB  and  SENDERENS,  Corn-pi,  rend.,  135,  226  (1902). 

29  FARBW.  MEISTER,  Lucius  and  BRUNING,  German  patent,  282,492  (1913). 

30  MIGNONAC,  Bull.  Soc.  Chim.  (4),  7,  154  (1910). 


139  HYDROGENATIONS  383 

wise  the  dinitrotoluenes  yield  the  cresyl-diamines  at  175-180°,  but 
above  190°  ammonia  is  split  off  and  the  toluidines  are  the  chief 
products.31 

381.  The  nitrophenols  hydrogenated  over  nickel  at  160-190°,  yield 
the  amino-phenols  regularly;  but  there  are  simultaneously  produced 
certain  amounts  of  ammonia  and  phenol  and  also  a  little  aniline.32 

382.  Esters  of  Nitrous  Acid.     It  is  stated  in  all  the  textbooks 
that  a  fundamental  distinction  between  the  nitrohydrocarbons  and 
their  isomers,  the  nitrites,  is  that  the  nitro  compounds  yield  amines 
on  hydrogenation,  while  the  nitrous  esters  are  either  not  affected  or 
give  the  alcohols  and  ammonia  without  any  amine. 

Gaudion  has  found  that  nitrous  esters  are  regularly  hydrogenated 
by  nickel  to  give  amines  exactly  like  their  isomers.  This  author  has 
worked  at  180°  with  methyl  and  ethyl  nitrites,  at  200°  with  propyl 
and  isopropyl,  and  at  220°  with  isobutyl  and  isoamyl. 

As  a  consequence  of  the  secondary  reaction  already  mentioned, 
all  three  amines,  primary,  secondary,  and  tertiary,  are  obtained,  the 
secondary  always  in  the  largest  quantity.  Thus  from  isoamyl  nitrite, 
31%  mono-,  62%  di-,  and  7%  tri-isoamyl-amines  are  obtained. 

The  discussion  of  these  facts  has  led  Gaudion  to  assume  that  there 
is  an  isomerization  of  the  nitrous  esters  into  the  nitro  bodies  at  the 
temperature  of  the  reaction.33 

The  reality  of  this  transformation  by  heat  alone  has  since  been 
established.  It  begins  at  100°  and  is  rapid  at  125-1300.34 

By  carrying  on  the  hydrogenation  at  low  temperatures,  around 
125-130°,  over  nickeled  asbestos,  the  unchanged  nitrous  esters  are 
hydrogenated  along  with  the  nitro  bodies  into  which  they  are  partly 
isomerized  so  that  there  is  simultaneous  production  of  ammonia  and 
the  corresponding  alcohol  from  the  nitrite  and  of  the  amine  from  the 
nitro  compound;  while  when  a  nitro  compound  is  hydrogenated,  the 
primary  amine  alone  is  formed  without  any  secondary  or  tertiary. 
This  is  the  case  with  methyl,  ethyl,  propyl,  isobutyl  and  isoamyl  ni- 
trites.35 

383.  Oximes.     In  the  aliphatic  series,  aldoximes  and  ketoximes 
are  readily  reduced  by  hydrogen  in  the  presence  of  nickel  at  180- 
220°  to  give  primary  and  secondary  amines  with  a  small  amount  of 
tertiary. 

With  acetoxime,  the  chief  product  is  diethyl  amine,  while  with 

31  MIGNONAC,  Butt.  Soc.  Chim.  (4),  7,  823  (1910). 

32  MIGNONAC,  Butt.  Soc.  Chim.  (4),  7,  270  (1910). 

33  GAUDION,  Ann,  Chim.  Phys.  (8),  25,  129  (1912). 

34  NEOGI  and  CHOWDURG,  J.  Chem.  Soc.,  109,  701  (1916). 

35  NEOGI  and  CHOWDURG,  J.  Chem.  Soc.,  in,  899  (1917). 


384  CATALYSIS  IN  ORGANIC  CHEMISTRY  140 

heptaldoxime,  C6H13 .  CH  :  N .  OH,  the  primary  amine  is  the  most 
abundant. 

The  oxime  of  acetone  gives  isopropyl-amine,  with  twice  as  much 
of  the  di-  and  a  little  of  the  tri-isopropyl-amine.  Analogous  results 
are  obtained  with  butanoxime (2) ,  C2H5(CH3)C  :  N  .  OH,  pentan- 
oxime(2),  pentanoxime(3),  and  2^-dimethyl  pentanoxime  (3)  ,38 

By  this  means  the  secondary  amines  from  secondary  alcohols  can 
be  prepared  with  good  yields,  a  class  of  substances  otherwise  difficult 
to  obtain. 

384.  This  method  can  also  be  applied  to  aromatic  aldoximes  in 
spite  of  the  difficulty  of  vaporizing  them  without  decomposition.    It 
is  best  to  operate  with  a  rapid  current  of  hydrogen  and  at  as  low  a 
temperature  as  possible.    Acetophenone-oxime,  C6H5 .  C  (  :  NOH)  .- 
CH3,  carried  thus  over  nickel  at  250-270°,  gives  a  small  amount  of 
the  primary  amine,  C6H5.CH(NH2)  .  CH3,  a  larger  amount  of  the 
secondary  amine  and  some  acetophenone  regenerated  by  the  action  of 
the  resulting  water  on  the  oxime. 

The  results  are  not  so  good  with  propiophenone-oxime,  from  which 
small  amounts  of  the  primary  and  secondary  amines  are  obtained 
along  with  much  phenylpropylene  and  phenylpropane,  and  still  poorer 
results  are  obtained  with  butyrophenone  oxime. 

On  the  contrary,  the  method  serves  well  with  benzophenone-oxime 
from  which  up  to  70%  of  the  primary  amine,  (C6H5)2CH  .NH2,  is 
obtained  with  a  certain  amount  of  the  secondary.37 

385.  The  ketoximes  of  the  cycloparaffines  react  in  an  analogous 
manner. 

The  hydrogenation  of  cyclohexanone-oxime  over  nickel  at  190- 
200°  gives  cyclohexyl-amine  regularly  with  a  little  dicyclohexyl 
amine  and  aniline.38  The  results  are  not  so  good  with  the  three 
methyl-cyclohexanone-oximes,  as  the  yields  of  the  amines  are  poor. 

CH2.CH2\ 

The  hydrogenation  of  cyclopentanone-oxime,       •  /C  :  NOH, 

CH2.CH2/ 

over  nickel  at  180°,  proceeds  smoothly  to  give  a  mixture  of  the  three 
cyclopentyl-amines,  the  secondary  forming  half  of  the  product  and 
the  primary  and  tertiary,  each  about  one-fourth.  Analogous  results 
are  obtained  with  methyl-cyclopentanone-oxime.59 

86  MAILHE,  Compt.  rend.,  140,  1691  (1905),  Ibid.,  141,  115  (1905)  and  Bull. 
Soc.  Chim.  (4),  15,  327  (1914). 

37  MAILHE  and  MURAT,  Butt.  Soc.  Chim.  (4),  9,  464  (1911). 

¥  AMOROUX,  Bull  Soc.  Chim.  (4),  9,  214  (1911). 

39  SABATIEB  and  MAILHE,  Compt.  rend.,  158,  985  (1914). 


141  HYDROGENATIONS  388 

Menthone-oxime  yields  the  primary  and  secondary  amines  and  a 
little  regenerated  menthone.40 

Camphor oxime,  when  hydrogenated  over  nickel  gives  the  corre- 
sponding amine  in  good  yield.41 

386.  Aliphatic  Amides.    Acetamide  is  readily  hydrogenated  at 
230°  by  nickel  with  the  production  of  water  and  ethylamine  and  also 
some  dimethylamine,  due  to  the  decomposition  of  the  primary  amine 
by  the  metal,  and  a  small  amount  of  ammonia. 

Propionamide,  CH3 .  CH2 .  CO  .  NH2,  gives  results  entirely  simi- 
lar.42 

387.  Ethyl  Acetoacetate.    Ethyl  acetoacetate,  the  ester  of  an 
unstable  /3-keto-acid,  gives,  when  hydrogenated  over  nickel,  a  triple 
reaction:  43 

1.  A  hydrogenation  by  substitution: 

CH3 .  CO  .  CH2 .  C02 .  C2H5  ->    CH3 .  CH2 .  CH2 .  C02 .  C2HS. 

ethyl  butyrate 

2.  A  breaking  up  of  the  molecule  into  the  fragments  CH3 .  CO  .- 
CH2-  and  -CO2 .  C2H5  which  are  hydrogenated  separately,  the  first 
into  acetone  and  then  isopropyl  alcohol  (435),  the  second  into  ethyl 
formate  which  is  decomposed,  under  the  reaction  conditions,  into 
ethyl  alcohol  and  carbon  monoxide  which  may  go  into  methane  (867) . 

3.  A  condensation  of  the  molecule  with  the  formation  of  solid 
dehydroacetic  acid,  (CH2  .C0)4,  which  is  produced  by  the  action  of 
heat  alone  on  ethyl  acetoacetate,44  and  which  the  presence  of  the 
nickel,  without  the  hydrogen,  causes  to  be  formed  at  250°: 

2  CH3 .  CO  .  CH2 .  C02 .  C2H6  =  (CH2CO)4  +  2C2H6 .  OH. 

388.  Aromatic  Aldehydes.     Contrary  to  what  takes  place  with 
aliphatic  aldehydes,  the  hydrogenation  of  aromatic  aldehydes  over 
nickel  does  not  reduce  them  to  alcohols,  but  tends  to  replace  the  oxy- 
gen by  hydrogen,  H2,  to  give  the  aromatic  hydrocarbons,  which  below 
250°  may  be  more  or  less  hydrogenated  to  the  cyclohexane  hydro- 
carbons.   There  is,  at  the  same  tune,  some  decomposition  of  the  alde- 
hyde   into    the    hydrocarbon    and    carbon    monoxide    (618).    Thus 
between  210   and   235°,    benzaldehyde    gives   toluene    and   benzene 
according  to  the  two  reactions: 

C6H5 .  CHO  +  2H2  =  H20  +  C6H5 .  CH3 
C6H5 .  CHO  =  CO  +  C6H6, 

40  MAILHE  and  MURAT,  Bull.  Soc.  Chim.  (4),  9,  464  (1911). 

41  ALOY  and  BRUSTIER,  Butt.  Soc.  Chim.  (4),  9,  734  (1911). 

42  MAILHE,  Bull.  Soc.  Chim.  (3),  35,  614  (1906). 

43  SABATIER  and  MAILHE,  Bull.  Soc.  Chim.  (4),  3,  232  (1908). 

44  GEUTHER,  Zeit.  /.  Chem.,  2,  8  (1866). 


389  CATALYSIS  IN  ORGANIC  CHEMISTRY  142 

and  these  are  accompanied  by  certain  proportions  of  methylcyclo- 
hexane  and  cydohexane,  the  carbon  monoxide  being  partly  reduced 
to  methane  (393)  .45 

389.  Aromatic    Ketones.     The    hydrogenation    of    aryl-aliphatic 
ketones,  effected  rapidly  over  a  nickel  of  only  moderate  activity  or 
at   a  temperature   above  250°,   is   limited  to   replacing  the   ketone 
oxygen  by  H2  with  the  production  of  the  corresponding  aromatic 
hydrocarbon.    Thus    acetophenone,    C6H5 .  CO .  CH3,     gives    ethyl- 
benzene,    C6H5.C2H5;     methyl-p.cresyl    ketone,    CH3 .  C6H4 .  CO  .- 
CH3,     yields     p. methyl-methyl     benzene;     p.tert-butyl-acetophenone, 
(CH3)3C  .  C6H4 .  CO  .  CH3,     gives     p.ethyl-tert-butyl-benzene;     and 
benzyl-acetone,  C6H5 .  CH2 .  CH2 .  CO  .  CH3,  yields  butyl-benzene*6 

But  when  the  hydrogenation  is  carried  on  at  180°,  with  an  active 
nickel  which  is  capable  of  hydrogenating  the  nucleus,  the  aromatic 
hydrocarbon  is  reduced  to  the  cyclohexane  derivative.  One  can  be 
sure  of  avoiding  this  complication  if  nickel  is  used  that  has  been  so 
altered  that  it  can  not  hydrogenate  benzene  or  if  the  operation  is 
carried  on  about  300°,  the  temperature  at  which  cyclohexane  deriva- 
tives are  dehydrogenated  even  in  excess  of  hydrogen.47 

It  is  the  same  way  with  diaryl  ketones  which  are  quantitatively 
reduced  to  the  corresponding  hydrocarbons  by  nickel  at  300°. 

Thus  benzophenone  at  300°  is  entirely  reduced  to  diphenylmethane, 
while  with  an  active  nickel  at  160°,  dicyclohexylmethane  is  formed. 

Desoxybenzo'ine,  C6H5 .  CH2 .  CO  .  C6H5,  yields  dibenzyl,  C6H5  .- 
CH2 .  CH2 .  C6H5,  at  350°.  Likewise  dibenzyl  ketone,  C6H5 .  CH2  .- 
CO .  CH2 .  C6H5,  is  70%  transformed  at  400°  into  symmetrical 
diphenylpropane,  which  is  accompanied  by  toluene  formed  by  the 
breaking  up  of  the  molecule  with  the  separation  of  carbon  monoxide 
which  is  reduced  to  methane.  The  same  hydrocarbon  is  formed  by 
the  hydrogenation  over  nickel  at  350°  of  phenyl-phenylethyl  ketone, 
C6H5 .  CO  .  CH2 .  CH2 .  C6H5.  48 

390.  Likewise    methyl-a-naphthyl-ketone    yields  a-ethylnaphtha- 
lene,  and  methyl-ff  -naphthyl  and  the  propyl-naphthyl  ketones  behave 
in  a  similar  manner.49 

Hexahydroanthrone  is  hydrogenated  at  200°  into  octohydroanthra- 
cene: 50 

45  SABATIER  and  SENDERENS,  Compt.  rend.,  137,  301   (1903). 
6  DARZENS,  Compt.  rend.,  139,  868  (1904). 

47  SABATIER  and  MURAT,  Ann.  Chim.  (9),  4,  263  (1915). 

48  SABATIER  and  MURAT,  Ann.  Chim.  (9),  4,  264  (1915). 

49  DARZENS  and  ROST,  Compt.  rend.,  146,  933  (1908). 
60  GODCHOT,  Bull.  Soc.  Chim.  (4),  i,  712  (1907). 


143  HYDROGENATIONS  392 


nk  /e4    —  » 

\CO  / 

Likewise   methyl(l)cyclopentanone(3)    is   advantageously   trans- 
formed at  250°  into  methy  Icy  clop  entane.51 


Dihydrocamphorone,  CH3 . CH;  )CH . CH(CH3)2,  is  hy- 

\CH2.CH2/ 

drogenated  at  180°  to  form  methyl-isopropyl-cyclopentane,  boiling  at 

391.  Aromatic   Diketones.     Similarly   to  the  monoketones,   the 
aromatic  diketones,  when  hydrogenated  over  nickel,  give  the  hydro- 
carbons.53 

Dibenzoyl,  C6H5 .  CO  .  CO  .  C6H5,  which  is  an  a  diketone,  is  hydro- 
genated over  nickel  at  220°  to  symmetrical  diphenylethane,  or  di- 
benzyl,  C6H5 .  CH2 .  CH2 .  C6H5,  beautiful  crystal  flakes,  without 
appreciable  secondary  reactions. 

Benzo'ine,  C6H5 .  CH(OH)  .  CO  .  C6H5,  gives  the  same  hydro- 
carbon as  the  sole  product  at  210-220°. 

Benzoyl-acetone,  C6H5  .  CO  .  CH2 .  CO  .  CH3,  which  is  a  ft  dike- 
tone,  when  hydrogenated  over  nickel  at  200°,  reacts  in  two  ways: 

1.  Butylbenzene  is  formed  to  an  extent  of  about  80%. 

2.  Following  a  general  tendency  of  ft  diketones,  there  is  a  break- 
ing up  into  two  fragments,  C6H5 .  CO-  and  -CH2 .  CO  .  CH3,  which 
are  hydrogenated  separately,  the  one  into  toluene  and  the  other  into 
acetone,  and  then  into  isopropyl  alcohol. 

392.  Anhydrides  of  Dibasic  Acids.     The  anhydrides  of  dibasic 
acids  which  have  been  submitted  to  hydrogenation  at  low  tempera- 
tures, have  given  only  the  corresponding  lactones. 

Succinic  anhydride  gave  butyrolactone : 54 

CH2.CO\  CH2.CH2v 

)0  ->    -  v. 

CH2.CO/  CH2.CO/ 

Over  nickel  at  200°,  phthalic  anhydride  yields  phthalid  quantita- 
tively: 

/OO\  /Oxl2\ 

C6H4(        )0  ->   C6H/         )0. 

\co/  \co  / 

51  ZELINSKY,  Berichte,  44,  2781  (1911). 

52  GODCHOT  and  TABOURY,  Compt.  rend.,  156,  470  (1913). 

53  SABATIER  and  MAILHE,  Compt.  rend.,  145,  1126   (1907). 
5*  EIJKMANN,  Chem.  Weekblad,  4,  191  (1907). 


393  CATALYSIS  IN  ORGANIC  CHEMISTRY  144 

Even  by  operating  at  130°  with  very  active  nickel  it  is  impossible 
to  replace  the  second  carbonyl.55 

In  the  same  manner  camphoric  anhydride  is  changed  into  campho- 
lid  exclusively:  54 


393.  Carbon  Monoxide.  The  direct  hydrogenation  of  carbon 
monoxide  over  nickel  gives  a  simple  method  for  the  synthesis  of 
methane: 

CO      3H  =  H0 


2 


The  reaction  commences  around  180-200°  and  goes  on  rapidly 
without  complications  at  230-250°.  With  the  theoretical  mixture  of 
hydrogen  and  carbon  monoxide,  3:1,  the  reaction  is  practically  com- 
plete, the  resulting  gas  being  nearly  pure  methane. 

The  nickel  is  not  sensibly  altered  by  the  reaction  when  it  is  car- 
ried on  below  250°  and  can  be  used  indefinitely.  On  cooling  it  is 
found  to  be  slightly  carbonized  but  still  pyrophoric  and  completely 
soluble  in  dilute  hydrochloric  acid  without  carbonaceous  residue. 

The  reaction  is  less  complete  when  the  carbon  monoxide  is  in  ex- 
cess; in  an  experiment  carried  out  with  85  volumes  of  carbon  mon- 
oxide to  51  volumes  of  hydrogen,  almost  one  third  of  the  hydrogen 
passed  through  the  tube  without  combining,  although  the  velocity  of 
the  gas  was  no  greater  than  in  the  experiment  quoted  above. 

394.  If  the  operation  is  carried  on  above  250°,  complications  arise 
due  to  the  special  effect  that  finely  divided  nickel  has  on  carbon  mon- 
oxide which  it  breaks  up  into  carbon  and  carbon  dioxide  (614)  : 

2CO  =  C  +  C02. 

The  carbon  dioxide  which  is  thus  formed  is  partially  hydrogenated. 
Its  proportion  is  greater,  the  higher  the  temperature,  since  the 
secondary  reaction  which  produces  it  is  greatly  accelerated  by  rise 
of  temperature. 

Thus  when  operating  at  380°  with  the  theoretical  mixture  which 
gives  methane  completely  at  250°,  a  gas  is  obtained  which  contains: 

Carbon  dioxide  ..................   10.5%  by  vol. 

Methane  ........................  67.9 

Hydrogen  .......................  21.6 

54  EIJKMANN,  Chem.  Weekblad,  4,  191  (1907). 

55  GODCHOT,  Bull,  Soc.  Chim.  (4),  i,  243  (1907). 


145  HYDROGENATIONS  397 

At  the  same  temperature,  water  gas,  equal  volumes  of  hydrogen 
and  carbon  monoxide,  gives  52.6%  carbon  dioxide,  39.8%  methane, 
and  1%  hydrogen. 

When  the  percentage  of  carbon  monoxide  is  still  further  increased, 
the  hydrogenation  is  greatly  weakened;  much  hydrogen  passes 
through  and  the  proportion  of  carbon  dioxide  becomes  very  large.56 

395.  Carbon  Dioxide.  Like  the  monoxide,  carbon  dioxide  is 
readily  hydrogenated  over  nickel  to  form  methane: 

C02  +  4H2  =  CH4  +  2H20. 

The  reaction  begins  at  a  higher  temperature  than  that  with  car- 
bon monoxide,  namely,  around  230°,  and  is  rapid  above  300°  and 
does  not  offer  any  considerable  complications  up  to  400°.  The  theory 
calls  for  four  volumes  of  hydrogen  to  one  of  carbon  dioxide.  With 
gas  mixtures  containing  a  larger  proportion  of  hydrogen,  the  carbon 
dioxide  disappears  almost  completely. 

Thus  in  an  experiment  with  82%  of  hydrogen  and  18%  carbon 
dioxide,  passed  through  the  tube  containing  the  nickel  at  the  rate  of 
55  cc.  per  minute,  the  issuing  gas  contained: 
With  the  nickel  at  258°  17.2%  by  vol.  carbon  dioxide 


1  283°   0.5%   "     " 


396.  Carried  on  at  300°  with  an  excess  of  hydrogen,  this  reaction 
gives  a  very  advantageous  method  for  preparing  pure  methane  if 
liquid  air  is  available  for  condensing  the  methane.    The  gas  is  washed 
with  caustic  potash  to  free  it  from  traces  of  carbon  dioxide,  dried  and 
the  methane  condensed,  leaving  the  hydrogen  as  gas.57 

397.  Application   to   the   Manufacture   of   Illuminating   Gas. 
The  production  of  methane  by  the  direct  hydrogenation  of  carbon 
dioxide  over  nickel  can  be  used  for  the  commercial  preparation  of  a 
gas  rich  in  methane  having  a  high  calorific  power  and  capable  of 
being  used  either  for  heating  or  for  lighting  by  using  incandescent 
mantles.58 

If  hydrogen  is  available  (produced  electrolytically  or  by  the  action 
of  iron  on  steam  at  a  red  heat) ,  the  hydrogenation  of  carbon  dioxide 
over  nickel  at  300  to  400°  is  an  excellent  way  to  prepare  methane.59 

But  the  preparation  of  the  hydrogen  costs  too  much  for  it  to  be 
used  for  the  manufacture  of  illuminating  gas.  One  must  start  with 

66  SABATIER  and  SENDERENS,  Compt.  rend.,  134,  514  (1902). 

67  SABATIER  and  SENDERENS,  Compt.  rend.,  134,  689  (1902). 

88  SABATIER,  VI  Internal.  Cong.  Pure  and  App.  Chem.,  Rome,  1906,  IV  sect, 
p.  188. 

89  SABATIER,  French  patent,  356,471,  June  17,  1905. 


398  CATALYSIS  IN  ORGANIC  CHEMISTRY  146 

a  cheap  commercial  gas  such  as  water  gas,  Riche  gas,  Siemens  gas, 
etc.  Various  methods  may  be  followed. 

398.  First  method.    Water  gas  obtained  by  the  action  of  steam 
on  red-hot  carbon  varies  in  composition  according  to  the  temperature 
at  which  it  is  prepared. 

At  a  bright  red,  there  are  equal  volumes  of  hydrogen  and  carbon 
monoxide: 

C  +  H20  =  CO  +  H2. 

At  a  lower  temperature  (a  very  dull  red)  there  are  only  carbon 
dioxide  and  hydrogen: 

C  +  2H20  =  C02  +  2H2. 

If  the  temperature  is  intermediate  (cherry  red),  the  reaction  is 
intermediate: 

2C  +  2H20  =  CO  +  C02  +  3H2. 

If  in  this  case  the  carbon  dioxide  be  removed  by  any  method  there 
remains  the  mixture  CO  +  3H2.  The  carbon  dioxide  may  be  ab- 
sorbed by  a  solution  of  potassium  carbonate  which  is  changed  to  the 
bicarbonate,  but  is  regenerated  with  evolution  of  carbon  dioxide  by 
boiling.  The  carbon  dioxide  may  be  solidified  by  refrigeration  or 
absorbed  in  cold  water  under  pressure.  The  residual  mixture, 
CO  +  3H2,  is  converted  into  pure  methane  by  passing  over  nickel 
at  230-250°,  5  volumes  of  water  gas  thus  furnishing  1  volume  of 
methane.  A  practical  difficulty  arises  from  the  fact  that  the  catalyst 
must  be  kept  between  230  and  250°,  since  above  250°  there  is  char- 
ring with  loss  of  carbon  and  fouling  of  the  nickel  resulting  in  a  rapid 
diminution  of  its  catalytic  power. 

399.  Second  Method.    The  operation  is  carried  on  in  two  phases: 
Water   gas   prepared   at   a   high   temperature    and   very   nearly 

CO  +  H2  is  passed  over  nickel  at  400  to  500°,  by  which  all  the  carbon 
monoxide  disappears  forming  either  methane  with  the  available  hy- 
drogen, or  splitting  up  into  carbon  dioxide  (614)  and  finely  divided 
carbon  which  is  deposited  on  the  nickel.  If  from  the  gas  so  produced, 
the  carbon  dioxide  is  absorbed,  the  remainder  is  very  rich  in  methane. 
For  the  conditions  cited  above  (394),  the  composition  would  be  83.8% 
methane  and  15%  hydrogen  with  a  calorific  power  of  7,800  calories 
per  cu.  m.,  while  the  original  gas  had  only  2,880.  This  is  the  gas  of 
the  first  phase. 

If  steam  be  passed  over  the  intimate  mixture  of  carbon  and  nickel 
obtained  above,  kept  at  400  to  500°,  the  carbon  reacts  rapidly  tend- 
ing to  give  hydrogen  and  carbon  dioxide  which  being  in  the  nascent 


147  HYDROGENATIONS  401 

state  react  to  give  a  certain  proportion  of  methane.  The  final  product 
is  a  mixture  of  hydrogen,  methane  and  carbon  dioxide  and  if  the  car- 
bon dioxide  is  eliminated,  there  remains  a  mixture  of  hydrogen  and 
methane  of  high  calorific  power  which  can  be  used.  This  is  the  gas 
of  the  second  phase,  less  rich  in  methane  than  the  first.  Its  formation 
has  eliminated  the  carbon  from  the  nickel  which  is  then  ready  to 
repeat  the  first  phase  of  the  reaction.60 

400.  Third  Method.    The  gas  of  the  second  phase  can  be  obtained 
alone  by  preparing  at  first  the  intimate  mixture  of  nickel  and  carbon 
by  the  action  of  finely  divided  nickel  on  various  gases  rich  in  carbon 
monoxide  such  as  Siemens  gas  or  producer  gas.    The  carbon  mon- 
oxide disappears  leaving  carbon  dioxide  and  carbon.    It  is  sufficient 
to  maintain  this  carbonaceous  mass  at  400  to  500°  and  pass  super- 
heated steam  over  it  to  have  a  mixture  of  methane,  hydrogen  and 
carbon  dioxide  which  can  be  used  after  the  latter  is  eliminated.61 

401.  Fourth  Method.    The  two  phases  of  the  reaction  that  have 
just  been  described  can  be  combined  in  practice.    All  that  is  required 
is  to  maintain  finely  divided  nickel  at  400  to  500°  and  pass  over  it  a 
mixture  of  suitable  proportions  of  water  gas   (or  Riche  gas  62)   and 
superheated  steam.    Under  these  conditions  the  carbon  monoxide  dis- 
appears and  is  replaced  by  hydrogen,  methane  and  carbon  dioxide, 
and  if  the  latter  is  eliminated,  we  have  in  one  operation  a  usable 
mixture  of  hydrogen  and  methane. 

This  method  of  operating  appears  economical.  The  amount  of 
nickel  required  for  the  reaction  is  less  than  1  k.  for  making  1  cu.  m. 
of  gas  per  hour.  Besides,  if  the  carbonated  gases  introduced  are  suit- 
ably purified  and  if  this  purification  is  completed  by  passing  over 
copper  turnings  heated  to  600°,  the  nickel  may  be  said  to  retain  its 
catalytic  power  indefinitely.  By  starting  with  water  gas  a  gas  is 
obtained  having  an  average  composition  of  48%  methane  and  52% 
hydrogen  and  having  a  calorific  power  of  5,800  calories  per  cu.  m. 
This  gas  does  not  contain  an  appreciable  amount  of  carbon  monoxide 
which  is  present  in  coal  gas  in  considerable  amount  (from  8  to  15%) 
and  which  renders  it  decidedly  toxic. 

In  fact  the  reactions  that  take  place  with  these  conditions  under 
the  influence  of  nickel  between  water  gas  and  steam  can  be  summed 
up  in  this  equation: 

5  (CO  +  H2)  +  H20  =  2CH4  +  2H2  +  3C02. 

water  gas 

60  SABATIER,  French  patent,  355,900,  July  5,  1905. 

61  SABATIER,  French  patent,  355,900,  1905. 

62  The  Riche  gas  is  a  mixture  of  carbon  monoxide,  hydrogen,  methane  and 
carbon  dioxide  prepared  by  heating  woody  or  cellulose  materials. 


402  CATALYSIS  IN  ORGANIC  CHEMISTRY  148 

Theoretically  5  volumes  of  perfect  water  gas  should  give  2  volumes 
of  the  mixture  containing  50%  methane.  In  practice,  as  the  water 
gas  contains  some  carbon  dioxide,  about  3  volumes  are  required  on 
the  average  for  1  volume  of  the  finished  gas. 

402.  The  use  of  industrial  refrigeration  permits  a  very  advan- 
tageous modification  of  the  first  process  (398) .    The  water  gas  should 
be  prepared  at  the  highest  possible  temperature  so  as  to  contain 
CO  +  H2  and  a  little  carbon  dioxide  and  nitrogen.    By  suitable  re- 
frigeration 75%  of  the  carbon  monoxide  can  be  liquefied  and  a  mix- 
ture of  CO  +  4H2  obtained  which  passing  over  nickel  at  200  to  250° 
would  furnish  exactly  the  gas  CH4  +  H2  equivalent  to  coal  gas.    The 
refrigeration  condenses  all  of  the  substances  that  may  be  toxic  to  the 
nickel  (sulphurous  gases,  etc.)  and  hence  guarantees  the  long  life  of 
the  catalyst. 

The  carbon  monoxide  separated  by  the  liquefaction  may  be  used 
for  heating  the  catalyzers  or  for  driving  motors.63 

403.  Aromatic  Halogen  Derivatives.    The  direct  reduction  of 
aromatic  halogen  derivatives  by  hydrogen  in  the  presence  of  nickel 
may  take  place  more  or  less  readily:    it  is  easy  with  chlorine  deriva- 
tives, less  easy  for  bromine  derivatives,  and  difficult  for  iodine  com- 
pounds ;  the  reason  being  easy  to  find  in  the  decreasing  affinity  of  the 
halogens  for  hydrogen  as  we  pass  from  chlorine  to  iodine,  since  the 
simultaneous  formation  of  the  hydro-acid  determines  the  substitution 
of  hydrogen. 

When  the  vapors  of  chlorbenzene  are  carried  by  hydrogen  over 
reduced  nickel  at  160°,  a  strong  absorption  of  hydrogen  is  noted  at 
once  and  a  little  cyclohexane  is  condensed  without  any  chlorcyclo- 
hexane.  The  chlorine  remains,  fixed  by  the  nickel,  the  surface  of 
which  loses  all  activity  by  being  changed  to  the  chloride.  After  a 
short  time  the  chlorbenzene  passes  through  unchanged. 

But  if  the  temperature  is  raised  above  270°  a  vigorous  evolution 
of  hydrochloric  acid  is  observed  and  a  readily  separated  mixture  of 
benzene  and  chlorbenzene  is  condensed.  At  the  same  time  there  is 
the  formation  of  crystals  of  diphenyl. 

In  contact  with  nickel  at  270°  or  above,  chlorbenzene  gives  nickel 
chloride,  and  the  liberated  residue,  C6H5-,  combines  with  hydrogen 
to  give  benzene  and  unites  with  itself  to  form  a  small  amount  of 
diphenyl.  But  at  this  temperature  the  nickel  chloride  is  reduced  by 
hydrogen  forming  hydrochloric  acid  and  regenerating  the  nickel  which 
repeats  the  reaction  indefinitely. 

404.  An   analogous   reduction   is   observed   when  the   polychlor- 

68  SABATIER,  Second  Congress  on  Refrigeration,  i,  115  (1912). 


149  HYDROGENATIONS  406 

derivatives  of  benzene  are  acted  on  by  hydrogen  in  the  presence  of 
nickel  above  270°;  the  chlorine  atoms  are  progressively  replaced  by 
hydrogen. 

Thus  m.dichlorbenzene  gives  a  mixture  containing: 

Benzene    30% 

Monochlorbenzene    60% 

Unchanged   dichlorbenzene    10% 

p.Dichlorbenzene  gives  35%  benzene  and  65%  monochlorbenzene. 

Perchlorbenzene,  C6C16,  acts  in  the  same  way  at  270°  and  gives 
a  mixture  of  the  trichlorbenzenes  (particularly  the  1,2,4),  dichlor- 
benzenes,  monochlorbenzene,  and  benzene. 

The  presence  of  aliphatic  side-chains  and  hydroxyl  groups  facili- 
tates the  reduction,  the  chlortoluenes  being  more  readily  reduced  than 
chlorbenzene. 

24,6-Trichlorphenol  is  readily  reduced  at  270°  and  gives  70% 
of  phenol  accompanied  by  monochlorphenols,  particularly  the  ortho. 

The  reduction  goes  even  better  with  amino  derivatives,  such  as 
the  chloranilines  which  give  aniline  hydrochloride  at  270°. 

The  chlornitrobenzenes  suffer  simultaneous  reduction  of  the  nitro 
group  and  elimination  of  the  chlorine,  furnishing  aniline  hydrochloride 
at  2700.64 

405.  It  can  be  foreseen  that  the  reduction  of  bromine  derivatives 
will  be  more  difficult,  since  the  temporary  nickel  bromide  is  less 
easily  reduced  by  hydrogen.    However,  the  reaction  can  be  carried 
out  well  with  monobrombenzene  at  270°  and  also  with  p.bromtoluene, 
the  bromanilines  and  the  bromnitrobenzenes. 

2,4,S-Tribromphenol  readily  yields  phenol  accompanied  by 
p.bromphenol  and  2}4^dibromphenol. 

406.  The  difficulties  are  greater  for  the  iodine  derivatives.    lodo- 
benzene  passed  over  nickel  with  hydrogen  at  270°  gives  no  lasting 
evolution  of  hydriodic  acid;  some  benzene  and  diphenyl  are  formed, 
but  the  reaction  stops,  since  the  nickel  is  not  restored  by  the  hydrogen 
and  does  not  continue  the  reaction. 

If  pure  hydrogen  is  passed  into  the  tube,  fumes  of  hydriodic  acid 
appear,  hence  nickel  iodide  is  reduced  by  hydrogen  at  270°  but  not 
in  the  presence  of  iodobenzene,  doubtless  because  this  compound 
gives  iodine  to  the  nickel  faster  than  the  hydrogen  can  remove  it. 
Practically,  the  reduction  of  iodobenzene  can  be  forced  by  alternately 
passing  pure  hydrogen  and  hydrogen  mixed  with  iodobenzene  vapors 

64  SABATIEB  and  MAILHE,  Compt.  rend.,  138,  245  (1904). 


407  CATALYSIS  IN  ORGANIC  CHEMISTRY  150 

over  the  nickel  at  270°.    But  under  these  conditions  the  metal  is  not 
a  true  catalyst.65 

407.  Esters  of  Halogenated  Aliphatic  Acids.  Vapors  of  ethyl 
mono-,  di-,  and  tri-Mor acetates,  when  passed  over  nickel  at  300°, 
with  excess  of  hydrogen,  are  reduced  to  ethyl  acetate,  the  chlorine 
atoms  being  successively  replaced  by  hydrogen.  Ethyl  bromacetate 
is  as  readily  reduced  to  ethyl  acetate.66 

65  SABATIER  and  MAILHE,  Compt.  rend.,  138,  245  (1904). 

66  SABATIER  and  MAILHE,  Compt.  rend.,  169,  758  (1919). 


CHAPTER   IX 
HYDROGENATIONS    (Continued) 

HYDROGEN ATIONS    IN    THE    GAS    PHASE  — USE 
OF  NICKEL   (Continued) 

ADDITION    OF   HYDROGEN 

408.  MANY  hydrogenations  correspond  to  the  fixation  of  hydrogen 
by  addition.    This  addition  takes  place  either  to  free  carbon,  whicji 
is  rare,  or  to  complex  molecules  containing  double  or  triple  bonds 
between  the  atoms.    We  will  examine  these  in  the  following  order: 

1.  Direct  fixation  by  carbon, 

2.  On  double  bond  between  two  carbon  atoms,  so-called  ethylene 
bond,  C  :  C, 

3.  On  triple  bond  between  two  carbon  atoms,  called  the  acetylene 
bond,  C  :  C, 

4.  Triple  bond  between  carbon  and  nitrogen,  C  i  N, 

5.  Quadruple  bond  between  carbon  and  nitrogen,  C  j  N, 

6.  Double  bond  between  carbon  and  an  oxygen  atom,  C  :  0, 

7.  Aromatic  nucleus, 

8.  Various  rings, 

9.  Carbon  disulphide. 

i.     Direct  Fixation  of  Hydrogen  by  Carbon 

409.  Berthelot  noted1  the  direct  union  of  hydrogen  and  carbon  at 
the  temperature  of  the  electric  arc *  to  form  acetylene  which  was 
necessarily  accompanied  by  some  methane  and  ethane  resulting  from 
the  pyrogenetic  decomposition  of  the  acetylene. 

Bone  and  Jerdan  state  that  carbon  unites  directly  with  hydrogen 
at  1200°  forming  1  to  2%  methane.2 

But  Berthelot,  carrying  out  the  reaction  with  pure  carbon  in  a 
quartz  tube,  could  not  confirm  the  formation  of  methane  and  con- 
cluded that  it  must  have  come  from  impurities  in  the  carbon  used  by 
the  English  chemists.3 

1  BERTHELOT,  Ann.  Chim.  Phys.  (4),  13,  143  (1868). 

2  BONE  and  JERDAN,  J.  Chem.  Soc.,  71,  42  (1897). 
8  BEBTHELOT,  Ann.  Chim.  Phys   (8),  6,  183  (1905). 

151 


410  CATALYSIS  IN  ORGANIC  CHEMISTRY  152 

410.  According  to  Henseling,  the  formation  of  methane  by  carbon 
and  hydrogen  begins  at  300°  in  the  presence  of  finely  divided  nickel. 

Sabatier  and  Senderens,  by  passing  hydrogen  at  250°  over  the 
intimate  mixture  of  carbon  and  nickel  which  is  formed  by  the  action 
of  reduced  nickel  on  carbon  monoxide  between  250  and  300°,  have 
definitely  proved  the  production  of  methane,  but  also  detected  water 
vapor.  After  some  time  the  formation  of  methane  ceased  though 
there  was  still  much  carbon  with  the  metal.  They  attributed  the 
formation  of  methane  and  water  to  the  presence  of  a  nickel  carbonyl 
combination  formed  by  the  action  of  the  carbon  monoxide.  The 
same  chemists  found  no  methane  when  the  carbonaceous  mixture  had 
been  prepared  above  400°,  a  temperature  at  which  carbonyl  com- 
pounds can  not  exist.* 

411.  Mayer  and  Altmayer  have  confirmed  the  very  slow  formation 
of  methane  from  carbon  in  contact  with  nickel  or  cobalt.    At  all  tem- 
peratures above  250°  methane  is  decomposed  by  nickel  into  carbon 
and  hydrogen,  the  amount  remaining  being  fixed  for  each  tempera- 
ture, and  the  same  whether  the  limit  be  approached  from  above  or 
from  below  as  is  true  with  all  reversible  reactions  (19),  and  not  al- 
tered when  cobalt  is  substituted  for  nickel.    The  amounts  of  methane 
at  equilibrium  are: 

At  250°  98.8%  by  volume 

536°  51.2% 

625°  24.7% 

850° 1.6% 

But  this  formation  is  very  slow  and  could  never  be  used  for  the 
preparation  of  methane.  The  velocities  of  the  mixtures  of  gases 
passed  over  the  mixture  of  carbon  and  nickel  to  obtain  the  equilibrium 
were  not  over  0.2  to  0.3  cc.  per  minute.6 

2.    Ethylene  Double  Bond 

412.  The  ethylene  double  bond  is  very  easily  attacked  by  direct 
hydrogenation  over  nickel  and  adds  two  atoms  of  hydrogen.    This  is 
readily  accomplished  by  nickel  reduced  above  500°  and  even  by  nickel 
which  has  been  weakened  by  the  action  of  poisons. 

413.  Hydrocarbons.    Ethylene  is  hydrogenated  by  nickel  from 
30°  up,  the  reaction  which  continues  indefinitely,  with  evolution  of 
heat,  gives  ethane  exclusively.    The  hydrogenation  is  more  rapid 
toward  130-150°. 6 

4  SABATIER  and  SENDERENS,  Bull  Soc.  Chim.  (4),  i,  107  (1907). 

6  MAYER  and  ALTMAYER,  Berichte,  40,  2134  (1907). 

6  SABATIER  and  SENDERENS,  Compt.  rend.,  124,  1359  (1897). 


153  HYDROGENATIONS  IN  THE  GAS  PHASE  414 

In  the  presence  of  excess  of  hydrogen,  all  the  ethylene  disappears, 
while  with  excess  of  ethylene  all  the  hydrogen  is  used  up  and  a  mix- 
ture of  ethane  and  ethylene  is  obtained  from  which  it  is  easy  to  re- 
move the  latter  by  bromine  water  leaving  the  ethane  pure. 

This  reaction  has  been  used  for  the  manufacture  of  ethane  for 
refrigerating  machines.  The  mixture  of  equal  volumes  of  ethylene 
and  hydrogen  is  passed  through  tubes  1  m.  long  and  7.5  cm.  in  diam- 
eter containing  reduced  nickel  and  heated  to  200°.  With  a  velocity 
of  2  cu.  m.  per  hour  a  gas  containing  80%  of  ethane  is  obtained.  In 
order  to  complete  the  union  of  hydrogen  and  ethylene  the  mixture 
is  compressed  to  30  or  40  atmospheres  in  a  vessel  filled  with  nickeled 
pumice.7 

Above  300°  nickel  decomposes  ethylene  (912)  with  the  liberation 
of  carbon,  and  the  production  of  methane  and  certain  amounts  of 
higher  paraffines  which  can  be  liquefied.6 

414.  Other  ethylene  hydrocarbons  can  be  transformed  into  the 
corresponding  saturated  hydrocarbons  below  160°  without  any  com- 
plications. But  above  200°  and  particularly  above  300°  there  can  be 
partial  breaking  of  the  carbon  chain  with  the  formation  of  saturated 
hydrocarbons  with  smaller  numbers  of  carbon  atoms  and  also  more 
complicated. 

With  propylene,  CH3.CH:CH2,  the  reaction  commences  in  the 
cold  and  up  to  200°  nothing  but  propane,  CH3 .  CH2 .  CH3,  is  produced 
so  long  as  the  hydrogen  is  in  slight  excess.  When  the  propylene  is  in 
excess,  particularly  above  290°,  small  amounts  of  higher  liquid  hydro- 
carbons with  petroleum  odors  are  formed,  and  at  higher  temperatures 
there  is  more  and  more  deposition  of  carbon  with  splitting  up  of  the 
propane. 

Trimethyl-ethylene,  or  2-methyl-butylene,  (CH3)  2C  :  CH  .  CH3, 
is  totally  hydrogenated  by  excess  of  hydrogen  into  pure  2-methyl- 
butane  or  isopentane,  at  150°. 

Likewise  hexene(2)  gives  hexane;  and  caprylene,  or  octene(l), 
octane  without  complications  below  160°. 8 

By  the  hydrogenation  of  2,2-dimethyl-methylene(3)-pentane,  over 
nickel  at  160°,  2,2,3-trimethyl-pentane,  boiling  at  110.5°  is  obtained, 
and  likewise  2 ^-dimethyl-heptane,  boiling  at  135°  from  2-ethyl- 
5-methyl-hexene* 

6  SABATIER  and  SENDERENS,  Compt.  Rend.,  124,  1359  (1897). 

7  SPRENT,  /.  Soc.  Chem.  Ind.,  32,  171  (1913). 

8  SABATIER  and  SENDERENS,  Compt.  rend.,  134,  1127  (1902). 

9  CLARK  and  JONES,  /.  Amer.  Chem.  Soc.,  34,  170  (1912).    CLARK  and  BEGGS, 
Ibid.,  34,  54  (1912). 


415  CATALYSIS  IN  ORGANIC   CHEMISTRY  154 

Likewise  nonene(2)  is  transformed  entirely  into  nonane.™ 
Methyl-propyl-octene    gives    the    corresponding    methyl-propyl- 
octane,  and  4;-cyclohexyl-heptene,  the  k-cyclohexyl-heptane.^ 

415.  In  the  case  of  phenyl-  or  polyphenyl-ethylene  hydrocarbons, 
when  the  hydrogenation  is  carried  out  with  a  weakened  nickel  such 
as  is  not  capable  of  hydrogenating  benzene  (56) ,  or  with  active  nickel 
at  300°,  the  aliphatic  double  bonds  are  saturated  without  hydrogenat- 
ing the  aromatic  nuclei. 

Thus  styrene,  C6H5 .  CH  :  CH2,  gives  only  ethyl-benzene, 
C6H5 .  CH2CH3. 

The  ortho,  meta,  and  para,  cresyl-propenes  (2)  are  regularly 
changed  into  the  ortho,  meta,  and  para  cymenes?-2 

l-Phenyl-2-propyl-pentene  yields  l-phenyl-2-propyl-pentane ."• 

Stilbene,  or  symmetrical  diphenyl  ethylene,  C6H5.CH:CH.C6H5, 
is  readily  transformed  by  a  slightly  active  nickel  at  240°  into  dibenzyl, 
C6H5.CH2.CH2.C6H5.  Likewise  aa-Diphenyl-ethylene  is  readily 
changed  to  aa-diphenyl-ethane,  l,2-diphenyl-propene(l)  and  1,1- 
diphenyl-propene(2)  furnish  the  corresponding  diphenyl-propanes  and 
similar  statements  hold  for  the  diphenyl-butenes  and  diphenyl- 
pentenes.™ 

Ocimene,  (CH3)2C:CH.CH2.CH:C.CH:CH2,  or  2fi-<Kmethyl-octa- 

CH3 

triene  (2,5,7),  of  oil  of  basil  is  readily  hydrogenated  over  nickel 
at  130-140°  to  the  corresponding  2,6-dimethyl-octane  boiling  at 
1580.14 

416.  Unsaturated    Alcohols.    The    fixation    of    hydrogen    fre- 
quently takes  place  without  alteration  of  the  alcohol  group. 

Propenol,  or  allyl  alcohol,  CH2  :  CH .  CH2OH,  is  readily  hydro- 
genated at  130-170°  over  nickel,  to  give  nearly  pure  propyl  alcohol 
containing  only  a  slight  amount  of  propionic  aldehyde.15 

Geraniol,  (CH3)2C:CH.CH2.CH2.C:CH.CH2OH,  or  2,Q-dimethyl- 

CH3 

octadiene  (2,6)  ol(8),  is  readily  hydrogenated  at  130-140°  to  give  the 
corresponding  dimethyl-octanol.  At  the  same  time  a  little  of  it  is 
reduced  to  the  saturated  hydrocarbon. 

10  CLARK  and  JONES,  J.  Amer.  Chem.  Soc.,  37,  2536  (1915). 

11  MURAT  and  AMOUROUX,  J.  Pharm.  Chim.  (7),  5,  473  (1912),  C.  A.,  7,  1494. 

12  SABATBBR  and  MURAT,  Compt.  rend.,  156,  184  (1913). 

13  SABATIER  and  MURAT,  Ann.  Chim.  (9),  4,  284-297  (1915). 

14  ENKLAAR,  Berichte,  41,  2085  (1908). 

15  SABATIER,  Compt.  rend.,  144,  879  (1907). 


155  HYDROGENATIONS  IN  THE  GAS  PHASE  419 

The  hydrogenation  of  linalool,  or  2fi-dimethyl-octadiene(2,7)- 
ol(6),  (CH3)2C  :  CH  .  CH2 .  CH2 .  C(OH)  .  CH  :  CH2,  furnishes  the 

CH3 

same  products.16 

Citronellol,    (CH3)  2C  :  CH  .  CH2  .  CH2 .  CH  .  CH2 .  CH2OH,   like- 

CH3 

wise  gives  dihydrocitronellol17 

We  have  seen  (208)  that  the  hydrogenation,  over  nickel  at  200°, 
of  secondary  a  -unsaturated  alcohols  gives  the  isomeric  saturated  ke- 
tone  instead  of  the  saturated  secondary  alcohol,  by  a  simple  migra- 
tion of  the  hydrogen  of  the  alcohol  group. 

417.  Esters.     The  esters  of  unsaturated  acids  are  readily  hydro- 
genated  over  nickel  whatever  be  the  position  of  the  double  bond. 

Esters  of  acrylic  acid  give  esters  of  propionic  at  180°. 

Ethyl  dimethyl-acrylate  likewise  gives  ethyl  isovalerate,  and 
ethyl  undecylenate,  the  undecylate. 

It  is  the  same  way  with  ethyl  cenanthylidene-acetate,  C6H13  .- 
CH  :  CH  .  C02 .  C2H5. 

The  same  fixation  of  hydrogen  takes  place  with  the  esters  of  un- 
saturated aromatic  acids  without  the  hydrogenation  of  the  nucleus. 
Methyl  cinnamate,  C6H5 .  CH  :  CH  .  C02 .  CH3,  gives  methyl  phenyl- 
propionate. 

Ethyl  phenyl-isocrotonate,  C6H5 .  CH  :  CH  .  CH2 .  C02 .  C2H6, 
acts  in  a  similar  manner.18 

418.  Ethers    of    Unsaturated    Alcohols.    The   vapors   of   allyl 
ether,  carried  by  an  excess  of  hydrogen  over  nickel  at  138-140°  are 
totally  changed  to  propyl  ether.19 

Isosajrol,        CH3.CH  :  CH.C6H3/    /CH2,      is  hydrogenated  in 

the  side  chain  to  dihydrosafrol  without  affecting  the  ether  group.20 

419.  Unsaturated    Aldehydes.    Acroleme,    CH2  :  CH  .  CHO,    is 
hydrogenated  over  nickel  at  160°  to  propionic  aldehyde,21  which  can 
be  further  hydrogenated,  by  a  slower  reaction,  to  propyl  alcohol. 

Likewise  cro tonic  aldehyde  over  nickel  at  125°  is  changed  to  buty- 

16  ENKLAAR,  Rec.  Trav.  Chim.  Pays-Bos,  27,  411   (1908),  and  Berichte,  41, 
2085  (1908). 

17  HALLER  and  MARTINE,  Compt.  rend.,  140,  1303  (1905). 

18  DARZENS,  Compt.  rend.,  144,  328  (1907). 

19  SABATIER,  Compt.  rend.,  144,  879  (1907). 

20  HENRARD,  Ch.  Wkbld.,  4,  630-2;  Chem.  Cent.,  1907  (2),  1512. 

21  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  399  (1905). 


420  CATALYSIS  IN  ORGANIC  CHEMISTRY  156 

ric  aldehyde  with  a  yield  of  50%,  with  about  20%  of  butyl  alcohol 
resulting  from  the  subsequent  hydrogenation  of  the  aldehyde.22 

420.  Unsaturated  Ketones.     The  fixation  of  hydrogen  on  ethy- 
lene  double  bonds  is  so  rapid  that  it  can  be  effected  before  the  ketone 
group,  -CO-,  is  changed  to  the  secondary  alcohol  group,  -CH(OH)-. 

Mesityl  oxide,  (CH3)2C  :  CH.CO.CH3,  is  transformed  at  160- 
170°  into  2-methyl-pentanone(4:))23  accompanied  by  some  of  the  cor- 
responding alcohol  and  even  of  isopentane.2*  Likewise  methyl- 
hexenone,  (CH3)2C  :  CH  .  CH2 .  CO  .  CH3 ,  gives  the  corresponding 
methyl-hexanone. 

3-Methyl-heptene(3)one(5)  is  transformed  at  180°  into  3-methyl- 
heptanone  (5) ,  and  likewise  2,4;,8-trimethyl-nonene(4:)one(6)  gives 
the  corresponding  saturated  ketone.25 

Phorone,  (CH3)2C  :  CH  .  CO  .  CH  :  C(CH3)2,  when  hydrogenated 
oV-er  nickel  at  160-170°,  is  totally  changed  to  di-isobutyl-ketone,  or 
isovalerone.26  By  operating  at  225°  the  ketone  is  accompanied  by 
the  alcohol  and  the  saturated  hydrocarbon.27 

421.  By  hydrogenating  pulegone  rapidly  over  nickel  at  140-160°, 
the  unsaturated  side  chain  can  be  hydrogenated  without  affecting  the 
ketone  group  to  give  pulegomenthone: 28 

/CO.CH2  \  /CO.CH2  \ 

(CH3)2C  :C(  ;CH.CH3-XCH3)2CH.CH(  ;CH.CH3. 

\CH2.CH2/  \CH2.CH2/ 


Camphorone,   CH3.CH(  )C :  C(CH3)2    is  hydrogenated 

\CH2.CH2/ 

over  nickel  at  130°  to  give  dihydrocamphorone,  boiling  at  182°. 29 

422.  Unsaturated  Acids.  Their  hydrogenation  is  readily  carried 
out  over  nickel  without  any  damage  to  the  catalytic  metal.  The 
vapors  of  crotonic  acid,  CH3 .  CH  :  CH  .  COOH,  at  190°  give  butyric 
acid  quantitatively.  The  vapors  of  ole'ic  acid,  carried  along  by  a 
violent  current  of  hydrogen  over  nickel  at  280-300°,  are  readily  trans- 
formed into  solid  stearic  acid,  and  the  same  is  true  of  its  isomer  ela'idic 
acid.30 

22  DOURIS,  Bull.  Soc.  Chim.  (4),  9,  922  (1911). 

23  DARZENS,  Compt.  rend.,  140,  152  (1905). 

24  SKITA,  Berichte,  41,  2938  (1908). 

26  BODROUX  and  TABOURY,  Compt.  rend.,  149,  422  (1909). 

26  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  16,  79  (1909). 

27  SKITA,  Loc.  cit. 

28  HALLER  and  MARTINE,  Compt.  rend.,  140,  1298  (1905). 

29  GODCHOT  and  TABOURY,  Compt.  rend.,  156,  470  (1913). 

30  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  16,  73  (1909). 


157  HYDROGENATIONS  IN  THE  GAS  PHASE  427 

3.     The  Acetylene  Triple  Bond 

423.  If  hydrogen  mixed  with  a  small  proportion  of  acetylene  is 
passed  over  cold  reduced  nickel,  the  metal  becomes  warm,  the  more 
so  when  the  proportion  of  acetylene  is  increased.    With  2  volumes 
of  hydrogen  to  1  of  acetylene  the  spontaneous  evolution  of  heat  may 
heat  the  end  of  the  nickel  train  to  150°.    The  contraction  of  the  gas 
is  enormous,  greater  than  corresponds  to  the  formation  of  ethane: 

C2H2  +  2H2  =  C2H6. 

The  volume  is  reduced  to  one  fourth,  although  a  little  unchanged 
acetylene  and  some  ethylene  remain,  showing  incomplete  hydrogena- 
tion,  because  there  is  produced  at  the  same  time  a  considerable  pro- 
portion of  higher  hydrocarbons,  part  of  which  are  liquefied.  The 
nickel  is  coated  with  a  little  carbon  which  is  readily  separated  by 
dilute  acids. 

On  the  contrary,  the  formation  of  ethane  is  complete  in  the  pres- 
ence of  an  excess  of  hydrogen. 

424.  Inversely  if  the  proportion  of  acetylene  in  the  mixture  is 
increased,  the  metal  heats  up  more,  the  liquids  formed  become  more 
abundant  and  the  presence  of  hydroaromatic  and  aromatic  hydro- 
carbons can  be  shown.    Finally,  an  incandescence  is  noticed  similar 
to  that  produced  by  acetylene  alone  on  nickel  (914)  .31 

425.  a-Heptine,  or  cenanthylidene,  is  readily  hydrogenated  over 
nickel  to  n.heptane*2 

4.     The  Triple  Bond  Between  Carbon  and  Nitrogen 

426.  The  direct  hydrogenation  of  nitriles,  R .  C  :  N,  easily  carried 
out  with  nickel,   leads  to  the   formation   of   the  primary   amines, 
R  .  CH2 .  NH2,  which  on  account  of  secondary  reactions  caused  by  the 
metal,  are  accompanied  by  secondary  and  tertiary  amines.    These 
reactions  correspond  to  the  formation  of  ammonia  which  is  eliminated, 
and  consequently  the  secondary  amine  constitutes  the  major  portion 
of  the  product.    We  have: 

2  R.CH2.NH2  =  NH3  +(R.CH2)2NH 

primary  amine  secondary  amine 

and        R .  CH2 . NH2  +  (R . CH2) 2NH  =  NH3  +  (R.CH2)3N. 

tertiary  amine 

427.  Aliphatic  Nitriles.  Formic-nitrile  or  hydrocyanic  acid  is  not 

31  SABATIER  and  SENDERENS,  Compt.  rend.,  128,  1173  (1899). 

32  SABATIER  and  SENDERENS,  Compt.  rend.,  135,  87  (1902). 


428  CATALYSIS  IN  ORGANIC  CHEMISTRY  158 

affected  by  hydrogenation  except  above  250°  but  then  gives  the  three 
methyl-amines  and  ammonia. 

Acetonitrile  is  readily  hydrogenated  at  200°  and  gives  a  mixture 
containing  60%  diethyl-amine,  and  20%  each  of  the  mono-  and  tri- 
amines. 

With  ethyl  cyanide,  the  dipropyl-amine  forms  nearly  80%  of  the 
product. 

Isoamyl  cyanide  likewise  gives  chiefly  secondary  amine,  the  pri- 
mary being  formed  in  least  amount.  The  amines  are  accompanied 
by  a  little  isopentane. 

It  is  evident  that  the  hydrogenation  of  aliphatic  nitriles  gives  us 
a  valuable  and  convenient  method  of  preparing  secondary  amines.33 

428.  Aromatic  Nitriles.     The  results  are  not  nearly  as  good  with 
aromatic  nitriles  from  which  the  hydrocarbons  and   ammonia   are 
formed. 

However,  the  hydrogenation  of  benzonitrile  at  250°  gives  a  certain 
proportion  of  benzyl-amine  and  dibenzyl-amine  and  the  same  is  true 
of  p.toluo-nitrile  which  gives  a  mixture  of  the  primary  and  secondary 
amines.34 

429.  Dicyanides.    Ethylene  dicyanide,  when  hydrogenated  over 
nickel,  gives  a  certain  proportion  of  tetramethylene-diamine  result- 
ing from  the  regular  hydrogenation: 

CN  .  CH2 .  CH2 .  CN  +  4H2  =  NH2 .  CH2 .  CH2 .  CH2 .  CH2 .  NH2. 
This    is    accompanied    by    a    little    ammonia    and    pyrrolidine, 

CH.2 .  CH2\ 

/NH,    resulting  from  its  decomposition.35 
CH2.CH2/ 

5.     Quadruple  Bond  Between  Carbon  and  Nitrogen 

430.  Carbylamines.     The  aliphatic  isocyanides,  or  carbylamines, 
R .  N  ?  C,  which  former  wet  reduction  methods  were  unable  to  hydro- 
genate  because  they  were  decomposed  by  hydration,  can  add  4H  over 
nickel  at  160-180°  to  form  the  secondary  amines,  R .  NH  .  CH3 

They  are  accompanied  by  a  small  amount  of  the  primary  amine, 
R  .  CH2 .  NH2,  and  the  secondary  amine,  (R  .  CH2)  2NH,  resulting 
from  the  hydrogenation  of  the  nitrile,  R .  C  i  N,  produced  by  partial 
isomerization  of  the  isocyanide. 

Methyl  carbylamine   gives  a  yield  of   80%   of   dimethyl-amine. 

83  SABATIER  and  SENDERENS,  Compt.  rend.,  140,  482  (1905). 

34  FREBAULT,  Compt.  rend.,  140,  1036  (1905). 

35  GAUDION,  Bull.  Soc.  Chim.  (4),  7,  824  (1910). 


159  HYDROGENATIONS  IN  THE  GAS  PHASE  432 

The  metal  is  gradually  coated  with  tarry  material  which  diminishes 
its  activity. 

Ethyl  carbylamine  gives  chiefly  methyl-ethyl-amine  with  a  little 
mono-  and  di-propyl  amines. 

Tertiary-butyl-isocyanide,  (CH3)3C.N  ;  C,  hydrogenated  at  170- 
180°,  gives  methyl-tert.butyl-amine,  which  has  never  been  obtained 
by  other  methods. 

If  the  reaction  is  carried  on  at  220-250°,  the  secondary  amine 
molecule  is  broken  up  with  the  formation  of  ammonia  and  hydro- 
carbon.36 

431.  Aliphatic  Carbimides.     It  is  convenient  to  consider  along 
with    the    carbylamines    the    aliphatic    carbimides,    or    isocyanates, 
R .  N  :  CO   (although  the  hydrogenation  is  not  simply  the  addition 
of  hydrogen  but  also  its  substitution  for  the  oxygen  atom),  because 
the  result  is  the  same  for  both  classes. 

Over  nickel  at  180-190°,  the  chief  reaction  is: 

R  .  N  :  CO  +  3H2  =  H20  +  R  .  NH  .  CH3. 

But  a  disturbance  is  caused  by  the  water  produced  which  reacts 
immediately  with  a  part  of  the  carbimide  to  form  a  disubstituted  urea, 
(R.NH)2CO,  and  carbon  dioxide.  The  alkyl  urea  is  immediately 
hydrogenated,  giving: 

(R  .  NH)2CO  +  3H2  =  H20  +  NH2 .  R  +  R  .  NH  .  CH3. 

Hence  there  is  a  certain  amount  of  the  primary  amine,  R .  NH2, 
and  on  account  of  secondary  actions  of  the  metal,  the  secondary, 
R2NH,  and  tertiary,  R3N,  also. 

Thus  ethyl  isocyanate  gives  a  considerable  amount  of  methyl- 
ethyl-amine,  a  little  diethyl-amine,  and  traces  of  ethyl-amine  and 
triethyl-amine.37 

6.     Double  Bond  between  Carbon  and  Oxygen 

432.  The  carbonyl  group,  CO,  which  frequently  occurs  in  organic 
compounds,  is  readily  hydrogenated  over  nickel  to  the  alcohol  group, 
CHOH. 

Aliphatic  Aldehydes.  Hydrogenated  over  nickel  below  180°, 
these  are  regularly  transformed  into  the  primary  alcohols  without  the 
production  of  di-secondary  glycols  or  acetals  as  by-products. 

Formaldehyde  vapors  at  90°  are  readily  transformed  and  methyl 

36  SABATIER  and  MAILHE,  Compt.  rend.,  144,  955  (1907). 

37  SABATIER  and  MAILHE,  Compt.  rend.,  144,  824  (1907). 


433  CATALYSIS  IN  ORGANIC  CHEMISTRY  160 

alcohol  is  condensed  along  with  water  which  is  due  to  the  formation 
of  methane  according  to  the  reaction: 

H  .  CO  .  H  +  2H2  =  CH4  +  H20. 

But  the  covering  over  of  the  metal  surface  with  a  thin  coating  of 
trioxy-methylene  soon  suppresses  its  activity.  If  the  temperature  is 
raised,  this  trouble  disappears,  but  the  formation  of  methane  increases 
as  well  as  the  decomposition  of  the  formaldehyde  itself  (508). 

Acetaldehyde  is  readily  transformed  into  alcohol  around  140°,  but 
at  200°  the  destruction  of  the  aldehyde  is  already  apparent. 

Propionaldehyde  is  regularly  hydrogenated  to  propyl  alcohol  be- 
tween 100  and  145°. 

It  is  the  same  with  isobutyric  and  isovaleric  aldehydes  at  135-160° 
which  yield  about  70%  of  the  alcohols,  the  rest  of  the  product  being 
unchanged  aldehyde  with  a  little  acetal. 

433.  Aromatic  Aldehydes.     These  do  not  give  this  reaction  but 
tend  to  form  the  hydrocarbons;  thus  benzaldehyde  at  210-235°  gives 
benzene  and  toluene  accompanied  by  a  certain  proportion  of  the  cor- 
responding   cyclohexane    compounds.       The    reaction    which    takes 
place  is: 

C6H5 .  CHO  +  2H2  =  C6H5 .  CH3  +  H20 

along  with  the  decomposition  of  benzaldehyde  by  nickel: 
C6H5.CO.H  =  C6H6  +  CO 

followed  by   a  partial   hydrogenation  of  the   carbon  monoxide  to 
methane.38 

434.  Pyromucic   Aldehyde.    Furfural,   or  pyromucic   aldehyde, 
C4H30  .  CHO,  hydrogenated  over  nickel  at  190°,  gives  furfuryl  alco- 
hol, C4H30 .  CH2OH,  accompanied  by  some  secondary  products  (see 
371  and  487)  ,39 

435.  Aliphatic  Ketones.    Aliphatic  ketones,  being  more  stable 
towards  nickel  than  the  aldehydes,  are  hydrogenated  regularly  into 
the  secondary  alcohols  and,  unlike  their  conduct  in  the  classic  reduc- 
tion by  sodium  amalgam,  they  do  not  form  any  secondary  products 
such  as  pinacones.    The  method  is  an  excellent  one  for  the  prepara- 
tion   of    many    secondary    alcohols,    which    are    produced    almost 
quantitatively. 

This  process  is  readily  applied  to  acetone  which  forms  isopropyl 
alcohol  at  115-125°  which  is  thus  prepared  quite  cheaply.  It  is  no 
less  good  for  butanone,  diethyl-ketone,  methyl-isopropyl-ketone, 

a8  SABATIEB  and  SENDERENS,  Compt.  rend.,  137,  301  (1903). 

39  PADOA  and  PONTI,  Lincei,  15  (2),  610  (1906),  C.,  1907  (1),  570. 


161  HYDROGENATIONS  IN  THE  GAS  PHASE  438 

methyl-propyl-ketone,  and  methyl-butyl-ketone.  It  is  only  above 
200°  that  decompositions  of  the  molecules  begin  to  take  place.40 

Diisopropyl  41  and  diisobutyl*2  ketones  are  readily  transformed 
into  the  secondary  alcohols  under  the  same  conditions. 

When  the  hydrogenation  of  ketones  is  carried  out  above  200° 
different  results  are  obtained.  Acetone  hydrogenated  between  200 
and  300°  gives  neither  isopropyl  alcohol  nor  its  pinacone,  but  chiefly 
methyl-isobutyl-ketone  (boiling  at  114°)  accompanied  by  diisobutyl- 
ketone  (b.1650).43 

Methyl-nonyl-ketone,  hydrogenated  at  300°,  does  not  give  the  cor- 
responding alcohol  but  various  products,  one  of  them  a  ketone, 

C22H440." 

436.  Alicyclic  Ketones.     The  method  is  readily  applied  to  these. 

Cyclopentanone  is  hydrogenated  over  nickel  at  125°  to  give  50% 
of  cyclopentanol,  a  little  cyclopentane,  and  40%  of  a  complex  ketone 
formed  by  the  joining  of  two  rings,  the  cyclopentyl-cyclopentanone.46 

The  a-  and  @-methylcyclopentanones  are  hydrogenated  at  150°  to 
the  corresponding  alcohols,  accompanied  by  greater  quantities  of  the 
dimethylcyclopentyl-pentanones  formed  by  the  union  of  two  rings.48 

Cyclohexanone  and  the  three  methyl-  cyclohexanones  are  regularly 
hydrogenated  below  180°  to  the  corresponding  alcohols  with  small 
amounts  of  the  hydrocarbons.47 

/CO.CH2\ 

Pulegomenthone,     (CH3)2CH  .  CH^  ;CH  .  CH3,      hydro- 


genated  by  an  active  nickel  at  140-160°,  gives  a  mixture  of  menthol 
and  pulegomenthol*8 

437.  Keto-acids.    Laevulinic  acid,  CH3  .  CO  .  CH2  .  CH2  .  COOH, 
hydrogenated  over  nickel  around  250°,  gives  the  hydroxy-acid,  which 
loses  water  to  form  valerolactone,  CH3  .  CH  .  CH2  .  CH2  .  CO.*9 

-0  -  1 

438.  Diketones.    The  results  of  the  hydrogenation  of  these  de- 
pend on  the  nature  of  the  compounds.50 

40  SABATIEB  and  SENDERENS,  Compt.  rend.,  137,  302  (1903). 

41  AMOUROUX,  Bull  Soc.  Chim.  (4),  7,  154  (1910). 

42  MAILHE,  Bull  Soc.  Chim.  (4),  15,  327  (1914). 

43  LASSIEUR,  Compt.  rend.,  156,  795  (1913). 

44  HALLER  and  LASSIEUR,  Compt.  rend.,  150,  1017  (1910). 

45  GODCHOT  and  TABOURY,  Compt.  rend.,  152,  881  (1911). 

48  GODCHOT  and  TABOURY,  Bull.  Soc.  Chim.  (4),  13,  591  (1913). 

47  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  402  (1905). 

48  HALLER  and  MARTINE,  Compt.  rend.,  140,  1298  (1905). 

49  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  16,  78  (1909). 

50  SABATIER  and  MAILHE,  Compt.  rend.,  144,  1086  (1907). 


439  CATALYSIS  IN  ORGANIC  CHEMISTRY  162 

a-Aliphatic  Diketones.  Diacetyl,  or  butamdione,  CH3 .  CO  .- 
CO  .  CH3,  by  hydrogenation  at  140-150°,  is  totally  transformed  into 
a  mixture  of  butanol-one  (2,3) ,  CH3 .  CH  (OH)  .  CO  .  CH3,  and 
butanediol(2,3),  CH3 .  CH(OH)  .  CH(OH)  .  CH3. 

439.  /3-Aliphatic  Diketones.  Acetyl-acetone,  CH3 .  CO  .  CH2 .- 
CO  .  CH3,  when  hydrogenated  at  150°,  gives  two  simultaneous  re- 
actions. One  part  is  normally  hydrogenated  to  form  pentol(2) one (4) , 
CH3 .  CH(OH)  .  CH2 .  CO  .  CH3,  while  the  larger  portion  is  split  into 
two  fragments: 

CH3 .  CO  .  CH2 .  CO  .  CH3  +  H2  =  CH3 .  CO  .  H  +  CH3 .  CO  .  CH3. 

The  acetaldehyde  and  acetone  thus  formed  are  then  reduced  to 
ethyl  and  isopropyl  alcohols. 

Methyl-acetyl-acetone,  CH3 .  CO  .  CH  (CH3)  .  CO  .  CH3,  forms 
hardly  anything  but  the  decomposition  products. 

440. 7  -Aliphatic  Diketones.  Acetonyl-acetone,  CH3 .  CO  .  CH2  .- 
CH2.CO.CH3,  when  hydrogenated  at  190°,  is  totally  trans- 
formed, not  into  the  corresponding  diol  but  into  the  ether, 
CH3 .  CH  .  CH2 .  CH2 .  CH  .  CH3,  produced  by  its  dehydration. 

I O- 

441.  Aromatic  Ketones.     Aromatic  ketones  and  diketones  give 
the  corresponding  alcohols  by  hydrogenation  but  go  chiefly  into  the 
hydrocarbons  (389  et  seq.). 

442.  Quinones.    We  can  consider  quinones  as  unsaturated  alicy- 
clic  diketones.     They  are  readily  hydrogenated  by  nickel  at  200°, 
and  add  H2  to  form  the  corresponding  diphenols  in  excellent  yields. 

This  is  the  case  with  ordinary  quinone  which  gives  hydroquinone 
quantitatively,  with  toluquinone,  with  p. xylo quinone,  and  with  thymo- 
quinone. 

But  if  the  operation  is  carried  on  at  a  higher  temperature,  220  to 
250°,  the  diphenol  is  no  longer  obtained,  but  water,  the  monophenol, 
and  even  the  hydrocarbon.51 

443.  Ethylene  Oxides.     The  direct  hydrogenation  of  these  oxides 
is  doubtless  readily  carried  out  in  all  cases. 

In  the  particular  case  of  the  ether  of  cyclohexanediol(I,2),  hydro- 
gen is  added  at  160°  to  give  a  quantitative  yield  of  cyclohexanol: 52 

CH2 .  CH2 .  CH\  CH2 .  CH2 .  CHOH 

•     )0  -*    - 
CH2 .  CH2 .  CH/  CH2 .  CH2 .  CH2 

61  SABATEER  and  MAILHE,  Compt.  rend.,  146,  457  (1908). 
52  BRUNEL,  Ann.  Chim.  Phys.  (8),  6,  237  (1905). 


163  HYDROGENATIONS  IN  THE  GAS  PHASE  446 

7.     The  Aromatic  Nucleus 

444.  The  direct  hydrogenation  of  the  aromatic  nucleus  has  long 
been  considered  very  difficult  to  accomplish.    When  benzene  is  re- 
duced by  concentrated  hydriodic  acid  at  250°,  cyclohexane,  C6H12, 
is  not  produced  as  was  hoped,  but  its  isomer,  methyl-pentamethylene, 
boiling  at  69°,  is  formed  by  a  molecular  rearrangement.53    However, 
this  method  of  reduction  has  been  successfully  used  with  toluene  and 
m.xylene  which  give  certain  amounts  of  the  corresponding  saturated 
cyclic  compounds.    But  this  formation  is  very  difficult  and  most  of 
the  aromatic  hydrocarbons  can  not  be  hydrogenated  in  this  way. 
The  hydroaromatic   hydrocarbons  might   be   separated   from   Baku 
petroleum    by    laborious    fractionations    or    prepared    by    tedious 
synthetic  processes. 

The  direct  hydrogenation  of  phenol  and  of  its  homologs  had  never 
been  accomplished,  nor  had  that  of  aniline  and  related  aromatic 
amines. 

On  the  contrary,  benzoic  and  the  phthalic  acids  had  been  hydro- 
genated by  sodium  amalgam. 

445.  In  1900,  Lunge  and  Akunoff  showed  that  combination  takes 
place  when  a  mixture  of  benzene  vapor  and  hydrogen  is  passed  over 
platinum  black  in  the  cold,  or  better,  at  100°,  and  calculated  from  the 
decrease  in  volume  of  the  mixture  that  cyclohexane,  C6H12,  must  have 
been  formed  although  the  same  reaction  with  platinum  sponge  gave 
only  cyclohexene,  C6H10.    But  the  activity  of  the  catalyst  was  quickly 
exhausted,  and  they  were  not  able  to  isolate  any  product  of  the  hydro- 
genation.5* 

The  use  of  reduced  nickel  enables  us  to  hydrogenate  the  aromatic 
nucleus  regularly  in  most  cases.  This  hydrogenation  ordinarily  takes 
place  around  180°  without  isomerization  and  usually  without  side 
reactions,  hence  with  good  yields.  This  is  without  doubt  the  most 
important  service  rendered  by  reduced  nickel. 

446.  Aromatic    Hydrocarbons.     The    direct    hydrogenation    of 
benzene  to  cyclohexane,  C6H12,  takes  place  with  nickel  above  70°. 
Its  speed  increases  with  the  temperature  up  to  170-190°,  where  it  is 
rapid  without  any  side  reaction.    Above  that,  and  particularly  above 
300°,  a  part  of  the  benzene  is  reduced  to  methane  and  carbon  is  de- 
posited on  the  nickel. 

Cyclohexane  is  sometimes  obtained  at  once,  but  usually  it  contains 
some  benzene  which  has  escaped  the  reaction  and  which  is  more 

53  KISHNER,  J.  prakt.  Chem.  (2),  56,  364  (1897). 

54  LUNGE  and  AKUNOFF,  Zeit.  anorgan.  Chem.,  24,  191   (1900). 


447  CATALYSIS  IN  ORGANIC  CHEMISTRY  164 

abundant  the  more  worn  out  the  nickel  is.  Treatment  with  a  mixture 
of  1  volume  fuming  nitric  acid  to  2  volumes  concentrated  sulphuric 
acid  easily  removes  the  benzene.55 

447.  All  of  the  homologs  of  benzene  are  hydrogenated  over  nickel 
at  150  to  180°,  being  transformed  into  the  homologs  of  cyclohexane. 

Below  250°  the  hydrogenation  takes  place  without  any  complica- 
tions with  the  methyl  derivatives  of  benzene,  toluene,  ortho,  meta, 
and  para  xylene,  mesitylene  and  pseudocumene,  the  yields  of  the  cor- 
responding methyl  cyclohexane  derivatives  being  practically  quanti- 
tative, though  traces  of  the  aromatic  hydrocarbons  remain.  These 
may  be  readily  eliminated  by  shaking  with  the  nitric-sulphuric  acid 
mixture  which  has  little  effect  on  the  saturated  hydrocarbons  in  the 
cold. 

448.  But  if  we  start  with  substituted  benzenes  containing  long 
side  chains,  ethyl,  propyl,  isopropyl,  and  butyl,  while  the  correspond- 
ing derivative  of  cyclohexane  is  always  the  chief  product,  there  is 
always  more  or  less  of  the  saturated  hydrocarbon  resulting  from  the 
shortening  of  the  long  side  chain.    Thus  ethyl-benzene  gives,  along 
with  ethyl-cyclohexane,  a  little  methyl-cyclohexane  with  correlative 
formation  of  methane.     Propyl-benzene   gives   a   little   ethyl-   and 
methyl-cyclohexane.    This  disturbance  is  more  serious  when  the  long 
side  chain  is  a  branched  one,  e.  g.,  isopropyl.    Thus  with  p.cymene 
which    is   p.methyl-isopropyl-benzene,    along    with    about    66%    of 
p.methyl-isopropyl-cyclohexane,  about  16%  each  of  p. dimethyl-  and 
p.methyl-ethyl-cyclohexane  are  obtained. 

This  formation  of  by-products  which  is  due  to  the  power  that  the 
nickel  has  of  dissociating  the  molecules,  is  greater  with  higher  tem- 
perature, and  for  that  reason  it  is  best  not  to  go  above  180°. 

449.  By  this  method,   methyl-cyclohexane,  the  three   dimethyl- 
cyclohexanes,  1,3,5-  and  1,3,4^-trimethyl-cyclohexanes,  propyl-cyclo- 
hexane,  p.methyl-ethyl-cyclohexane,  isopropyl-cyclohexane,  the  three 
methyl-isopropyl-cyclohexanes  or  menthanes,  and  dimethyl-isobutyl- 
cyclohexane  have  been  prepared.56 

450.  Above  250°,  and  particularly  above  300°,  the  production  of 
the  cyclohexane  hydrocarbons  diminishes  and  then  disappears  alto- 
gether since  the  inverse  dehydrogenation  begins  and  becomes  more 
and  more  rapid  (641). 

451.  Phenyl-ethylene,  styrene,  or  cinnamine,  C6H5 .  CH  :  CH2,  is 

55  SABATIEB  and  SENDERENS,  Compt.  rend.,  132,  210  (1901). 

66  SABATIEB  and  SENDERENS,  Compt.  rend.,  132,  566  and  1254  (1901). 
SABATIEB  and  MURAT,  Compt.  rend.,  156,  184  (1913),  and  Ann.  Chim.  (9),  4,  271 
(1915). 


165  HYDROGENATIONS  IN  THE  GAS  PHASE  453 

hydrogenated  at  160°  by  an  active  nickel  to  ethyl-cyclohexane.  With 
a  slightly  active  nickel  around  200°  hardly  anything  but  ethyl- 
benzene  is  obtained.57 

Phenyl-acetylene,  C6H5 .  C  i  CH,  hydrogenated  over  nickel  at 
180°,  gives  almost  exclusively  ethyl-cyclohexane. ,58 

452.  Polycyclic  Aromatic  Hydrocarbons.     Hydrogenation  over 
active  nickel  at  about  170°  permits  the  addition  of  6  atoms  of  hydro- 
gen to  each  aromatic  nucleus.    The  low  volatility  of  the  polyphenyl 
hydrocarbons,  which  do  not  boil  except  at  temperatures  above  250°, 
makes  it  necessary  to  carry  their  vapors  along  by  a  large  excess  of 
hydrogen.    A  single  passage  over  the  nickel  under  the  conditions  used 
for  benzene  does  not  effect  complete  hydrogenation  and  it  is  usually 
necessary  to  repeat  the  process  with  the  product. 

However,  a  single  operation  is  all  that  is  required  to  transform 
diphenyl-methane,  C6H5 .  CH2 .  C6H5,  into  dicyclohexyl-methane, 
C9Htt.GHt.C,Hu.« 

With  diphenyl,  C6H5 .  C6H5,  Eijkman 59  obtained  only  phenyl- 
cyclohexane,  C6H6 .  CgR^,  boiling  at  240°,  but  Sabatier  and  Murat 
have  succeeded  in  transforming  it  into  dicyclohexyl,  C^^  .  C6H1:l, 
melting  at  4°  and  boiling  at  233°  and  almost  unattacked  by  the  mix- 
ture of  nitric  and  sulphuric  acids.60 

Likewise  symmetrical  diphenyl-ethane,  or  dibenzyl,  C6H5 .  CH2  .- 
CH2 .  C6H5,  has  been  completely  transformed  into  1,2-dicyclohexyl- 
ethane,  C6H±1 .  CH2 .  CH2 .  C^,  boiling  at  270°.  The  1,1-diphenyl- 
ethane,  (C6H5)2CH .  CH3,  is  changed  with  greater  difficulty  into  the 
1,1-dicyclohexyl-ethane  boiling  at  256°. 

The  four  diphenyl-propanes  are  more  or  less  readily  transformed 
into  the  dicyclohexyl-propanes  over  nickel  at  around  170°. 

Only  in  the  case  of  dimethyl-diphenyl-methane,  (C6H6)2C(CH3)2, 
a  quaternary  hydrocarbon,  is  there  any  notable  breaking  up  of  the 
molecule  into  isopropyl-cyclohexane,  ethyl-cyclohexane,  methyl- 
cyclohexane  and  even  cyclohexane. 

Five  diphenyl-butanes  have  been  easily  hydrogenated  over  active 
nickel  at  170°,  to  the  corresponding  dicyclohexyl-butanes,  and  like 
results  have  been  obtained  with  three  diphenyl-pentanes  which  do  not 
boil  below  about  300°. 61 

453.  According  to  whether  the  temperature  is  higher  or  lower, 
triphenyl-methane,     CH(C6H6)3,     gives     first     dicyclohexyl-phenyl- 

57  SABATIER  and  SENDERENS,  Compt.  rend.,  132,  1255  (1901). 

58  SABATIER  and  SENDERENS,  Compt.  rend.,  135,  88  (1902). 

«»  EIJKMAN,  Chem.  Weekblad,  i,  7  (1903),  C.,  1903  (2),  989. 

60  SABATIER  and  MURAT,  Compt.  rend.,  154,  1390  (1912). 

61  SABATIER  and  MURAT,  Ann.  Chim.  (9),  4,  303  (1915). 


454  CATALYSIS  IN  ORGANIC  CHEMISTRY  166 


methane,  C6H5  .  CHfCgHn)^  and  then  tricyclohexyl-methane, 
CH(C6H11)3.62 

On  the  contrary,  the  hydrogenation  of  symmetrical  tetraphenyl- 
ethane,  (C6H5)2CH  .  CH(C6H5)2,  has  miscarried,  since  under  the  in- 
fluence of  very  active  nickel  at  230-240°,  it  yields  only  dicyclohexyl- 
methane  produced  by  the  hydrogenation  of  the  two  halves  of  the 
molecule.63 

454.  Hydrindene,  which  can  be  regarded  as  benzene  with  a  satu- 

/CH2v 
rated  side  chain,        C6BL  )CH2,          adds  6  atoms  of  hydrogen 


to  form  dicyclononane,  C9H16,  boiling  at  163°.  64 

C6H5\ 
Fluorene,      •  CH2,      over  nickel  at  150°,  furnishes  only  the 


decahydro-fluorene  boiling  at  258°.  65 

455.  Aromatic  Ketones.    With  an  active  nickel  at  a  moderate 
temperature,  the  -CO-  group  is  changed  to  -CH2-  and  the  aromatic 
rings  are  hydrogenated  (389)  . 

Thus  acetophenone  gives  ethyl-cyclohexane. 

Dibenzyl-ketone,  C6H5  .  CH2  .  CO  .  CH2  .  C6H5,  with  active  nickel 
at  1750,66  can  give  immediately  symmetrical  dicyclohexyl-propane, 
CgHn  .  CH2  .  CH2  .  CH2  .  C0HU. 

456.  Phenols.     The  direct  hydrogenation  of  the  aromatic  nucleus 
can  be  readily  accomplished  in  phenol  and  its  homologs  by  the  use 
of  nickel. 

Phenol,  hydrogenated  at  180°,  gives  immediately  cyclohexanol, 
CoH-u  .  OH,  containing  5  to  10%  unchanged  phenol,  small  quantities 
cyclohexanone  and  cyclohexene,  C6H10.  The  mixture  boiling  between 
155  and  165°  can  be  purified  by  a  second  passage  over  the  nickel  at 
150-170°  which  changes  the  phenol  and  cyclohexanone  completely  into 
cyclohexanol.67 

457.  o.Cresol  is  regularly  transformed  by  nickel  at  200-220°  into 
o.methyl-cyclohexanol  with  a  yield  of  better  than  90%.    There  is 
a  little  of  the  ketone  which  can  be  extracted  with  sodium  bisulphite. 

m.Cresol,  under  the  same  conditions,  gives  a  mixture  of  the  alcohol 

62  GODCHOT,  Compt.  rend.,  147,  1057  (1908). 

63  SABATIER  and  MURAT,  Compt.  rend.,  157,  1497  (1913). 

64  EIJKMAN,  Chem.  Weekblad,  i,  7  (1903),  C.,  1903  (2),  989. 

65  SCHMIDT  and  METZGER,  Berichte,  40,  4566  (1907). 

66  SABATIER  and  MURAT,  Compt.  rend.,  155,  385  (1912). 

67  SABATIER  and  SENDERENS,  Compt.  rend.,  137,  1025  (1903). 


167  HYDROGENATIONS  IN  THE  GAS  PHASE  461 

and  ketone  which  can  be  rehydrogenated  at  180°  to  give  practically 
pure  m.methyl-cyclohexanol. 

p.Cresol  is  readily  hydrogenated  at  200-230°  to  form  p.methyl- 
cyclohexanol  containing  only  traces  of  the  ketone  which  are  readily 
eliminated  by  bisulphite.68 

458.  The  xylenols,  or  dimethyl-phenols,   are  hydrogenated  over 
nickel  with  varying  degrees  of  success.     I  ^-Dimethyl-phenol^) ,  at 
190-200°,  changes  almost  completely  to  the  corresponding  dimethyl- 
cyclohexanol  with  a  little  ketone  and  m.xylene. 

The  same  may  be  said  of  the  l,4^dimethyl-phenol(2),  which  gives 
the  corresponding  cyclohexanol  with  about  10%  of  the  ketone. 

l,2-Dimethyl-phenol(4),  hydrogenated  under  the  same  conditions, 
gives  only  about  25%  of  the  desired  cyclohexanol,  about  8%  of  the 
ketone,  while  about  67%  is  reduced  to  o.xylene.Qg 

459.  In  the  same  manner  with  an  active  nickel  at  below  160°  the 
regular  hydrogenation   of  p. butyl-phenol ,   methyl-butyl-phenol,   one 
dimethyl-butyl-phenol™  and  one  diethyl  phenol 71  have  been  hydro- 
genated into  the  corresponding  cyclo-aliphatic  alcohols. 

Thymol  is  satisfactorily  hydrogenated  to  hexahydrothymol  at 
180-185°. 

The  same  may  be  said  of  its  isomer  carvacrol,  which  is  hydrogen- 
ated at  195-200°  to  hexahydrocarvacrol.™ 

460.  Polyphenols.    The  addition  of  6H  to  the  nucleus  in  poly- 
phenols  is  difficult  to  realize  by  the  use  of  nickel,  doubtless  because 
the  desired  reaction  can  be  effected  only  between  narrow  temperature 
limdts.    At  200°  the  hydrogenation  leads  to  phenol   and   benzene, 
mixed  with  cyclohexanol  and  cyclohexane,  without  any  appreciable 
amount  of  the  desired  cycloaliphatic  diols  or  triols.73 

461.  On  the   contrary,  by  lowering   the  temperature  to   around 
130°,  the  normal  addition  of  hydrogen  can  be  accomplished  in  some 
cases. 

Hydroquinone  at  130°,  gives,  exclusively  cyclohexadiol  (1,4),  or 
quinite,  as  the  cis  form,  but  if  the  hydrogenation  is  carried  on  at  160°, 
a  mixture  of  the  cis  and  trans  forms  is  obtained  with  some  phenol 
and  cyclohexanol. 

Pyrocatechin,  at  130°,  gives  exclusively  cyclohexadiol (1, ,2),  melt- 
ing at  75°. 

68  SABATIER  and  MAILHE,  Compt.  rend.,  140,  350  (1905). 

69  SABATIER  and  MAILHE,  Compt.  fend.,  142,  553  (1906). 

70  DARZENS  and  HOST,  Compt.  rend.,  152,  607  (1911). 

71  HENDERSON  and  BOYD,  /.  Chem.  Soc.,  99,  2159  (1911). 

72  BRUNEL,  Compt.  rend.,  137,  1268  (1903). 

73  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  428  (1905). 


462  CATALYSIS  IN  ORGANIC  CHEMISTRY  168 

Resorcine  is  difficult  to  hydrogenate  at  low  temperatures  on 
account  of  its  slight  volatility,  but  small  amounts  of  cyclohexa- 
diol(l,3),  melting  at  65°,  have  been  isolated.74 

462.  Pyrogallol,  at  120-130°,  gives  cyclohexatriol(  1,2,3),  melting 
at  67°.74 

463.  Thymoquinol,   C3H7(CH3)C6H2(OH)2,   is   hydrogenated   by 
nickel  to  menthane-diol(2,5),  melting  at  1120.75 

464.  Ethers  of  Phenol.    By  means  of  nickel,  below  150°,  we 
may  accomplish  the  direct  hydrogenation  of  phenol  ethers  without 
breaking  up  the  molecules. 

Thus  anisol,  C6H5 .  OCH3,  gives  methoxy-cyclohexane,  CgH^  .- 
OCH3.  The  methyl  ethers  of  the  cresols  are  transformed  into  the 
corresponding  methoxy-methyl-cyclohexanols.  Phenetol  gives  ethoxy- 
cyclohexanol.™ 

465.  Aromatic  Alcohols.  Up  to  the  present,  the  hydrogenation 
over  nickel  has  not  been  accomplished  without  eliminating  the  hy- 
droxyl  group.    Thus  benzyl  alcohol  gives  toluene  and  methyl-cyclo- 
hexane. 

p.Tolyl-dimethyl-carbinol,  CH3 .  C6H4  .  C  (OH)  (CH3)  2,  changes 
to  hexahydrocyynene,  identical  with  menthane,  when  hydrogenated  at 
1500.77 

466.  Aromatic    Amines.     On    hydrogenating    aniline    at    190°, 
ammonia  is  evolved  and  a  nearly  colorless  liquid  with  strong  ammo- 
niacal  odor  is  obtained  which  gives  on  fractionation: 

1.  A  little  benzene  and  cyclohexane,  going  over  around  80°, 

2.  About  30%  of  cydohexyl-amine,  CgH^  .  NH2,  boiling  at  134°, 

3.  A  small  amount  of  unchanged  aniline,  boiling  at  182°, 

4.  A    portion    boiling    above    190°,    consisting    of    about    30% 
dicyclohexyl-amine  y    boiling    at    252°,    and    about    30%    of    cyclo- 
hexyl-aniline,  boiling  at  279°,  and  a  little  diphenyl-amine ,  boiling 
at  311°. 

The  dicyclohexyl-amine  comes  from  the  decomposition  of  the 
cyclohexyl-amine  by  the  nickel,  with  elimination  of  ammonia,  simi- 
lar to  what  has  been  mentioned  in  connection  with  the  hydrogenation 
of  nitriles  (426).  The  cyclohexyl-aniline  and  the  diphenyl-amine 
can  be  regarded  as  produced  by  the  partial  dehydrogenation  of  the 
dicyclohexyl-amine.78 

74  SABATIER  and  MAILHE,  Compt.  rend.,  146,  1193  (1908). 

76  HENDERSON  and  SUTHERLAND,  J.  Chem.  Soc.,  97,  1616  (1910). 

76  BRUNEL,  Ann.  Chim.  Phys.  (8),  6,  205  (1905).    SABATIER  and  SENDERENS, 
Bull.  Soc.  Chim.  (3),  33,  616  (1905). 

77  SMIRNOV,  J.  Russian  Phys.  Chem.  Soc.,  41,  1374  (1909). 

78  SABATIER  and  SENDERENS,  Compt,  rend.,  138,  457  (1906). 


169  HYDROGENATIONS  IN  THE  GAS  PHASE  470 

467.  The  toluidines,  CH3 .  C6H4 .  NH2,  are  more  difficult  to  hydro- 
genate  than  aniline,  but  appear  to  give  similar  results. 

By  operating  with  m.toluidine  (boiling  at  197°)  over  nickel  at 
200°,  we  obtain,  along  with  a  little  methyl-cyclohexane,  boiling  at 
101°,  and  unchanged  m.toluidine,  a  considerable  amount  of  metho- 
cyclohexyl-amine,  CH3 .  C6H10 .  NH2,  boiling  around  150°  and  having 
an  intensely  alkaline  reaction,  and  higher  alkaline  products  boiling 
at  145  and  175°  respectively  under  20  mm.  pressure,  which  are  doubt- 
less dimethocyclohexyl-amine  and  methocyclohexyl-aniline.  But  the 
activity  of  the  nickel  falls  off  rapidly  to  nothing.  This  effect  is  even 
more  marked  with  ortho  and  para  toluidines  and  with  the  xylidines, 
whether  these  amines  contain  toxic  substances  or  whether  slightly 
volatile  products  of  the  reaction  remain  on  the  surface  of  the  nickel 
and  suppress  its  activity.79 

468.  The  hydrogenation  of  the  nucleus  by  nickel  at  160-180°  is 
more  readily  accomplished  for  anilines  substituted  in  the  NH2-  group. 
The  most  difficult  of  these  is  methyl-aniline  which  gives  a  rather 
moderate  yield  of  cyclohexyl-methyl-amine.    A  secondary  reaction, 
which  becomes  more  and  more  important  as  the  temperature  is  raised, 
tends  to  produce  the  aliphatic  amine,  with  the  simultaneous  libera- 
tion of  cyclohexane  or  benzene. 

Much  more  satisfactory  results  are  obtained  with  ethyl-aniline, 
which  gives  cyclohexyl-ethyl-amine,  boiling  at  164°,  with  dimethyl- 
aniline,  which  leads  to  cyclohexyl-dimethyl-amine,  boiling  at  165°, 
and  with  diethyl-aniline  which  yields  cyclohexyl-diethyl-amine, 
boiling  at  1930.80 

469.  Diphenyl-amine,  (C6H5)2NH,  when  submitted  to  hydrogena- 
tion over  nickel  at  250°,  is  decomposed  into  ammonia  and  cyclohexane. 
But  by  working  at  190-210°  with  vapors  of  diphenyl-amine  carried 
along  by  a  large  excess  of  hydrogen,  it  is  possible  to  accomplish  a 
regular  hydrogenation,  producing  cydohexyl-aniline  and  dicyclohexyl- 
am.ine,  accompanied  by  certain  amounts  of  cyclohexane,  cyclohexyl- 
amine,  and  even  aniline,  resulting  from  the  breaking  up  of  the  mole- 
cule by  nickel.81 

470.  Benzyl-amine,  such  as  is  usually  obtained  by  various  methods 
of  preparation,  can  not  be  hydrogenated  over  nickel  without  break- 
ing up  of  the  molecule  into  ammonia  and  toluene,  even  below  100°. 
The  cause  must  be  the  presence  of  foreign  substances  which  injure 
the  catalyst,  since  the  normal  hydrogenation  can  be  realized  with 

79  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  387  (1905). 

80  SABATIER  and  SENDERENS,  Compt.  rend.,  138,  1257  (1904). 

81  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  483  (1905). 


471  CATALYSIS  IN  ORGANIC  CHEMISTRY  170 

benzyl-amine  obtained  by  the  catalytic  action  of  thoria  on  a  mixture 
of  ammonia  and  benzyl  alcohol  vapors,  and  hexahydrobenzyl-amine 
is  obtained,  accompanied  by  dihexahydrobenzyl-amine82 

471.  Aromatic   Acids.    Direct  hydrogenation  over  nickel   fails 
when  it  is  applied  to  benzoic  acid  or  its  homologs.    When  the  vapors 
of  benzoic  acid,  carried  along  by  an  excess  of  hydrogen,  are  passed 
over  a  very  active  nickel  at  180-200°,  the  production  of  a  little 
cyclohexane  and  traces  of  hexahydrobenzoic  acid  is  observed  at  the 
start,  but  after  a  very  short  time  the  benzoic  acid  passes  on  un- 
changed, the  surface  of  the  nickel  having  doubtless  become  coated 
with  a  stable  benzoate.83 

Sabatier  and  Senderens  failed  likewise  in  the  hydrogenation  of 
the  esters  of  benzoic  acid,  as  the  nickel  rapidly  became  inactive.  But 
by  operating  with  the  metal  block  at  a  perfectly  regulated  tempera- 
ture below  170°,  Sabatier  and  Murat  have  succeeded  in  accomplishing 
the  regular  hydrogenation  of  methyl  benzoate,  and  even  more  readily, 
the  hydrogenation  of  the  esters  of  higher  alcohols,  and  have  thus  ob- 
tained methyl,  ethyl,  isobutyl,  and  isoamyl  hexahydrobenzoates,  the 
isoamyl  ester  in  80%  yield.  The  saponification  of  these  esters  yields 
the  hexahydrobenzoic  acid  immediately.84 

By  the  same  method,  they  realized  the  complete  hydrogenation 
of  esters  of  phenyl-acetic  acid  to  those  of  cyclohexyl-acetic  at  170- 
1850,85  of  esters  of  hydrocinnamic  acid  to  esters  of  ($-cyclohexyl- 
propionic86  and  finally  of  esters  of  ortho,  meta,  and  para  toluic  acids 
to  those  of  the  corresponding  hexahydro  toluic  acids. 

8.    Various  Ring  Compounds 

472.  Trimethylene      Ring.      Cyclopropane,     or     trimethylene, 
CH2\ 


/,     is  hydrogenated  by  nickel  above  80°,  and  rapidly  at 
CH2/ 
120°,  to  form  propane.87 

Likewise    ethyl-trimethylene    is    hydrogenated    by    nickel    to 
isopentane: 

CH2\  CH3\ 

•       ;CH.CH2.CH3  ->  )CH.CH2.CH3.88 

CH2/  CHs/ 

82  SABATIER  and  MAILHE,  Compt.  rend.,  153,  160  (1911). 

83  SABATIER  and  MURAT,  Compt.  rend.,  154,  923  (1912). 

84  SABATIER  and  MURAT,  Compt.  rend.,  154,  924  (1912). 

85  SABATIER  and  MURAT,  Compt.  rend.,  156,  424  (1913). 

86  SABATIER  and  MURAT,  Compt.  rend.,  156,  751  (1913). 

87  WILLSTATTER  and  KAMETAKA,  Berichte,  41,  1480  (1908). 

88  ROZANOV,  /.  Russian  Phys.  Chem.  Soc.,  48,  168  (1916),  C.  A^  n,  454. 


171  HYDROGENATIONS  IN  THE  GAS  PHASE  476 

Methyl-cyclopropene  yields  isobutane  at  170-180°  :  89 


CH3\ 

•     ;c.GH3  -»        )CH.CH3. 

CH2/  CH3/ 

Dimethylmethylene-cyclo-propanp  gives  isohexane  at  160°:  90 


•       ;C:C(CH3)2  ->    CH3.CH2CH2CH(CH3)2 
CH2/ 

473.  Tetramethylene     Ring.      Cyclobutane    furnishes     butane, 
while  cyclobutene,  at  180°,  passes  first  into  cyclobutane  and  then  into 
butane.91 

474.  Pentamethylene   Ring.     Cyclopentadiene  is  regularly  hy- 
drogenated  to  cyclopentane92 

475.  Hexamethylene  Ring.     Cyclohexene,  C6H10,  is  readily  re- 
duced to  the  cyclohexane  condition  by  nickel  below  180°.    The  same 
is  true  of  the  cyclohexadienes. 

All  the  cyclohexene  hydrocarbons  are  readily  hydrogenated  by 
nickel  to  the  cyclohexane  hydrocarbons.  Thus  the  ethylene  hydro- 
carbons formed  from  the  three  dimethyl-cyclohexanols  readily 
furnish  the  three  dimethyl-cyclohexanes.93  Methyl-ethyl-l,2-cyclo- 
hexene  regularly  passes  into  the  corresponding  saturated  deriva- 
tive.94 

Menthene,  CH3  .  C6H8  .  C3H7,  submits  to  regular  hydrogenation 
at  175°  to  give  p.methyl-isopropyl-cyclohexane,  or  menthane,  iden- 
tical with  that  formed  from  cymene  and  accompanied  by  certain 
amounts  of  the  same  secondary  products  95  (448)  . 

Phenyl-cyclohexene(l,l)  is  readily  changed  to  phenyl-cyclohexane 
by  a  slightly  active  nickel.  The  same  is  true  of  cyclohexyl-cyclo- 
hexene(l,l),  which  furnishes  dicyclohexyl*6 

476.  Acetyl-  cyclohexane,   CH6  .  CO  .  CeH^,   is   hydrogenated   by 
nickel  at  160°,  without  affecting  the  ketone  group,  to  give  hexahydro- 
acetophenone.97 

Ethyl  tetrahydrobenzoate,  C6H9  .  C02C2H5,   is  transformed  into 

89  MERESHKOWSKI,  J.  Russian  Phys.  Chem.  Soc.,  46,  97  (1914),  C.  A.,  8,  1965. 

90  ZELINSKY,  Berichte,  40,  4743  (1907). 

91  WILLSTATTER  and  BRUCE,  Berichte,  40,  4456  (1907). 

92  EIJKMAN,  Chem.  Weekblad,  i,  7  (1903). 

93  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  10,  552,  555  and  559  (1907). 
9*  MURAT,  Bull.  Soc.  Chim.  (4),  i,  774  (1907). 

95  SABATIER  and  SENDERENS,  Compt.  rend.,  132,  1256  (1901). 

96  SABATIER  and  MKJRAT,  Compt.  rend.,  154,  1390  (1912). 

97  DARZENS  and  HOST,  Compt.  rend.,  151,  758  (1910). 


477  CATALYSIS  IN  ORGANIC  CHEMISTRY  172 

ethyl  hexahydrobenzoate,  and  the  ester  of  cyclohexene-acetic  acid, 
C6H9  .  CH2  .  C02H,  into  that  of  hexahydrophenyl-acetic  acid.98 

Carvone  adds  hydrogen  to  its  double  bond  and  its  ketone  group 
passes  into  the  alcohol,  forming  a  mixture  of  hydrocarvols." 

477.  Terpenes.    The  terpenes  with  two  double  bonds  add  2H2 
with  nickel  at  180°,  while  the  terpenes  with  one  double  bond  usually 
add  only  H2. 

Limonene  gives  menthane,  identical  with  that  from  menthene  and 
cymene  with  the  same  secondary  products.  The  same  is  true  of 
sylvestrene  and  terpinene. 

Pinene  is  readily  transformed  at  170-180°  into  dihydropinene, 
C10H18,  boiling  at  166°,  identical  with  that  prepared  by  the  action  of 
hydroiodic  acid  (Berthelot). 

The  camphene  (from  an  unknown  source),  melting  at  41°,  studied 
by  Sabatier  and  Senderens,  added  H2  with  difficulty  at  165-175°  to 
furnish  a  camphane,  C10H18,  boiling  at  164°  and  appearing  to  be 
identical  with  that  which  Berthelot  had  previously  isolated.100 

The  camphene  from  pinene  hydrochloride  gave  a  mixture  of  a 
solid  camphane,  melting  at  65-67°,  and  liquid  camphane  ,  boiling  at 
1600.101 

An  inactive  camphene  melting  at  47-49°  was  transformed  into  a 
solid  camphane,  melting  at  60°,  by  a  single  hydrogenation  over 
nickel.102 

478.  Terpineol,  hydrogenated  over  nickel,  even  at  a  low  tempera- 
ture, around  125°,  is  changed  to  hexahydrocymene.103 


a-Thujene,  CH3.C  ,  -  7C.CH(CH8)2,  changes  into    hexa. 

hydrocymene.10* 

479.  Heptamethylene    Ring.    Cycloheptadiene,    C7H10,    hydro- 
genated over  nickel  at  180°,  yields  only  cycloheptane,  stable  even 
with  prolonged  hydrogenation   at  200°,   but   at  235°    it   seems  to 
isomerize  into  methyl-cyclohexane.™5 

480.  Octamethylene    Ring.      Cyclo-octadiene,   C8H12,   hydroge- 

98  DARZENS,  Compt.  rend.,  144,  328  (1907). 

99  HALLER  and  MARTINB,  Compt.  rend.,  140,  1302  (1905). 

100  SABATIER  and  SENDERENS,  Compt.  rend.,  132,  1256  (1901). 

101  LIPP,  Annalen,  382,  265  (1911). 

102  NAMETKIN  and  Miss  ABAUMOVSKAYA,  /.  Russian  Phys.  Chem.  Soc.,  47, 
414  (1915),  C.  A.,  10,  45. 

103  HALLER  and  MARTINB,  Compt.  rend.,  140,  1393  (1905). 
10*  ZEOLINSKY,  J.  Russian  Phys.  Chem.  Soc.,  36,  768  (1904). 
106  WILLSTATTER  and  KAMEKATA,  Berichte,  41,  1480  (1908). 


173  HYDROGENATIONS  IN  THE  GAS  PHASE  484 


106 

16) 


nated  very  slowly  over  nickel  at  180°,  gives  cyclo-octane,  C8H 
which  further  hydrogenation  at  200-250°  appears  simply  to  isomerize 
into  dimethyl-cyclohexane.107 

Bicyclo-octene,  at  150°,  furnishes  bicy  do-octane,  boiling  at 
1400.108 

481.  Naphthalene  Nucleus.    Naphthalene  is  transformed  at  200° 
by  nickel  into  tetrahydronaphthalene,109  boiling  at  205  °,110  while  at 
175°,    decahydronaphthalene,    or    naphthane,    boiling    at    187°,    is 
formed.111 

a-Naphthol,  by  means  of  two  successive  hydrogenations  at  170° 
and  135°,  respectively,  is  transformed  into  decahydro-a-naphthol, 
melting  at  62°. 

Likewise  by  hydrogenation  at  170°  and  then  at  150°,  /3-naphthol 
yields  decahydro-/3-naphthol,  melting  at  75°.112 

/CH 

482.  Acenaphthene,  CioHe,    |      2,  which  is  related  to  naphthalene 

\ 


in  constitution,  is  transformed  by   nickel  at  210°,   as  well   as   at 
250°,  into  the  tetrahydro-,  C12H14,  boiling  at  254°.  113 

483.  Anthracene  Nucleus.    Anthracene  is  hydrogenated  in  steps, 
more  hydrogen  being  taken  up   at   lower  temperatures.    At  260° 
tetrahydroanthracene,  C14H14,  melting  at  89°,  is  formed,  while  at  200°, 
octohydroanthracene,  melting  at  71°,  is  obtained.    By  using  a  very 
active  recently  prepared  nickel,  it  is  possible  to  transform  the  octo- 
hydro-  into  perhydroanthracene,  C14H24,  melting  at  88°.  114 

484.  Phenanthrene  Nucleus.     Phenanthrene,  C14H10,  hydrogen- 
ated at  160°  over  a  very  active  nickel,  gave  a  mixture  of  the  hexa- 

106  WILLSTATTER  and  VERAGUTH,  Berichte,  40,  957  (1907). 

107  WILLSTATTER  and  WASER,  Berichte,  44,  3444  (1911). 

108  WILLSTATTER  and  VERAGUTH,  Berichte,  41,  1480  (1908). 

109  The  tetrahydro  has  d.  0.91520  and  boils  at  205-207°   and  is  known  as 
tetralin  while  the  dekahydro  is  known  as  dekalin  and  has  d.  0.882720  and  boils 
at  189-191°.    Tetralin  spirits  is  a  mixture  of  the  two.    These  are  coming  to  be 
important  as  turpentine  substitutes,  particularly  in  Europe.    See  DE  KEGHEL, 
Rev.  chim.  ind.,  29,  173-178  (1920),  C.  A.,  14,  3803;  also  SHROETER,  Annalen,  426, 
1  (1922).  —  E.  E.  R. 

110  SABATIER  and  SENDERENS,  Compt.  rend.,  132,  1257  (1901). 

111  LEROUX,  Compt.  rend.,  139,  672  (1904). 

112  LEROUX,  Compt.  rend.,  141,  953  (1905).      Ann.  Chim.  Phys.  (8),  21,  483 
(1910). 

118  SABATIER   and   SENDERENS,   Compt.   rend.,    132,    1257    (1901).    GODCHOT, 
Bull  Soc.  Chim.  (4),  3,  529  (1908). 

114  GODCHOT,  Ann.  Chim.  Phys.  (8),  12,  468  (1907). 


485  CATALYSIS  IN  ORGANIC  CHEMISTRY  174 

hydro-,  boiling  at  305°,  and  the  octohydro-,  C14H18,  boiling  at  2800.118 
These  results  are  different  from  those  obtained  by  Schmidt  and 
Metzger,  who  got  only  dihydrophenanthrene  at  150°,  116  and  from 
those  of  Padoa  and  Fabris,  who  obtained  a  mixture  of  the  solid 
dihydro-  and  the  liquid  tetrahydro-  at  200°,  but  were  able  to  get  the 
dodecahydro-  at  1750.117 

485.  Complex  Rings.    Pyrrol,  when  hydrogenated  over  nickel  at 
180-190°,  gives  25%  of  pyrrolidine,  C4H9N,  with  a  small  quantity  of 
a  substance  which  appears  to  be  hexahydro-indoline™ 

486.  Pyridine   is   only   slowly   attacked  by   hydrogenation   over 
nickel  between  120  and  220°,  and  does  not  yield  any  piperidine; 
there  is  opening  of  the  ring  with  the  formation  of  some  amyl-amine™9 

487.  Furfuryl-ethyl-carbinol       yields       tetrahydrojurjuryl-ethyl- 
carbinol  on  hydrogenation  at  1750.120 

Methyl-a-fufurane  adds  2H2  at  190°  to  give  tetrahydro-methyl- 


a-furfurane,  /  .       If  the  hydrogenation  is  pushed, 


the  ring  is  opened  and  methyl-propyl-ketone  is  formed,  finally  methyl- 
propyl-carbinol,  or  pentanol(2)  ,121 

488.  Quinoline,  when  hydrogenated  over  a  very  active  nickel  at 
160-190°,  adds  2H2  to  the  pyridine  ring  to  form  tetrahydroqmnoline 
in  excellent  yield. 

Likewise  6-methyl-quinoline  is  readily  hydrogenated  to  the  corre- 
sponding methyl-tetrahydroquinoline*22 

By  carrying  out  the  hydrogenation  at  130-140°,  over  a  very  ac- 
tive nickel,  decahydroquinoline  may  be  obtained.  Likewise  quin- 
aldine  furnishes  decahydroquinaldine  in  excellent  yield.123 

489.  By   hydrogenating  quinoline   at  a  higher  temperature,  the 
normal  addition  of  hydrogen  does  not  take  place,  but  the  ring  is 
opened  to  yield  ethyl-o.toluidine,  which  does  not  remain  as  such  but 
closes  the  ring,  with  loss  of  hydrogen  to  givea-methyl-indol:  12* 

us  BRETEAU,  Compt.  rend.,  140,  942  (1905). 

116  SCHMIDT  and  METZGER,  Berichte,  40,  4240  (1907). 

117  PADOA  and  FABRIS,  Gaz.  Chim.  ltd.,  39  (1),  333  (1909). 
us  PADOA,  Gaz.  Chim.  Hal,  36  (2),  317  (1906). 

ii9  SABATIER  and  MAILHE,  Compt.  rend.,  144,  784  (1907). 
12°  DOURIS,  Compt.  rend.,  157,  722  (1913). 

121  PADOA  and  PONTI,  Lincei,  15  (2),  610  (1906),  C.,  1907  (1),  570. 

122  DARZENS,  Compt.  rend.,  149,  1001  (1909). 

123  SABATIER  and  MURAT,  Compt.  rend.,  158,  309  (1914). 

12*  PADOA  and  CARUGHI,  Lincei,  15,  113  (1906),  C.,  1906  (2),  1011. 


175  HYDROGENATIONS  IN  THE  GAS  PHASE  493 

CH      CH  CH  CH 

HC        C        CH    HC        C.CHS  HC         C  -  CH 

I          I          I    -»     I          I  -      I          I          II 

HC        C        CH    HC        C.NH.CH2          HC        C         C.CH3 

W  XC/          CH8  W 

490.  Carbazol,  diphenyl-imide,  when  hydrogenated  over  nickel  at 
200°  under  10  atmospheres  pressure,  gives  a/3-dimethyl-indol:  125 


.CH 


491.  Acridine  is  slowly  hydrogenated  over  nickel  at  250-270°  to 

ap-dimethyl-quinoline:  126 


HC  X)  C.CH3 


C 


9.     Carbon  Bisulphide 

492.  When  carbon  disulphide  vapors  are  carried  by  an  excess  of 
hydrogen  over  nickel  at  180°,  a  volatile,  extremely  ill-smelling  sub- 
stance is  produced  which  gives  a  yellow  mercury  salt,  a  white  cad- 
mium salt,  and  brown  lead  and  copper  salts,  and  which  appears  to  be 
methylene-dithiol,  H2C(SH)2.127 

HYDROGENATIONS   WITH   DECOMPOSITIONS 

493.  Catalytic  nickel  quite  frequently  exercises  a  more  or  less 
intense  decomposing  action  on  the  molecules:    in  such  cases  not  only 
the  original  compound  but  also  the  fragments  resulting  from  its 
decomposition  are  hydrogenated. 

Hydrocarbons.  We  shall  study  in  Chapter  XXI  the  decom- 
positions that  hydrocarbons  undergo  at  high  temperatures  in  the 
presence  of  nickel  and  other  catalysts.  The  study  of  the  simultaneous 
hydrogenations  can  not  be  separated  from  that  of  the  decompositions 
and  molecular  condensations  resulting  therefrom. 

125  PADOA  and  CHIAVES,  Lined,  16  (2),  762  (1907),  C.,  1908  (1),  649. 

126  PADOA  and  FABRIS,  Lincei,  16  (1),  921  (1907),  C.,  1907  (2),  612. 
"7  SABATIER  and  ESPIL,  Bull  Soc.  Chim.  (4),  15,  228  (1914). 


494  CATALYSIS  IN  ORGANIC  CHEMISTRY  176 

494.  Aliphatic   and   Aromatic   Ethers.    Aliphatic   ethers   resist 
hydrogenation  over  nickel  quite  well,  but  when  it  is  carried  out  above 
250°,  there  is  decomposition  into  hydrocarbon  and  alcohol  which  is 
then  attacked,  furnishing  the  products  of  the  hydrogenation  of  its 
debris. 

Thus  ethyl  ether  gives  ethane  and  alcohol  which  gives  the  frag- 
ments of  acetaldehyde,  of  which  the  carbon  monoxide  is  partly 
changed  to  methane:  128 

(C2H5)20  +  H2  =  C2H6  +  CH3 .  CH2OH 
then  CH3 .  CH2OH  =  CH4  +  CO  +  H2 

CO  +  3H2  =  CH4  +  H20. 

Aromatic  ethers  undergo  an  analogous  decomposition  with  nickel, 
this  taking  place  at  moderate  temperatures  with  the  mixed  alkyl 
phenyl  ethers  and  greatly  diminishing  the  yields  of  the  mixed  alkyl- 
cyclo-aliphatic  ethers  which  are  made  by  their  hydrogenation. 

In  the  hydrogenation  of  anisol  to  methoxy-cyclohexane  (464), 
there  is  the  production  of  certain  amounts  of  methyl  alcohol  and 
cyclohexane™8  If  the  operation  is  carried  on  above  300°,  there  is  no 
hydrogenation  of  the  nucleus  and  scission  is  rapid  in  the  same 
manner  as  with  aliphatic  ethers. 

We  have  two  reactions: 

C6H5 .  0  .  R  +  H2  =  RH  +  C6H5 .  OH 

phenol 

and  C6H6 .  0  .  R  +  H2  =  C6H6  +  R  .  OH 

alcohol 

the  alcohol  itself  being  more  or  less  broken  down  by  the  hydrogena- 
tion. 

This  is  the  case  with  the  methyl  ethers  of  phenol,  of  the  three 
cresols,  of  a-naphthol,  etc.,  and  also  with  phenyl  oxide  which  is  the 
most  resistant  to  decomposition.129 

495.  Phenyl  Isocyanate.     Phenyl  isocyanate,  when  hydrogenated 
over  nickel  at  190°,  breaks  up  into  two  portions  which  are  hydro- 
genated separately: 

C6H6 .  N  :  CO  =  CO  +  C6H5 .  N-. 

We  obtain  aniline  and  carbon  monoxide  which  yields  methane 
with  the  formation  of  water.  This  reacts  quantitatively  with  the 
original  compound  to  give  carbon  dioxide  and  solid  diphenyl-urea.1*0 

128  SABATIER  and  SENDERENS,  Bull  Soc.  Chim.  (3),  33,  616  (1905). 

"9  MAILHE  and  MURAT,  Bull.  Soc.  Chim.  (4),  n,  122  (1912). 

130  SABATIER  and  MAILHE,  Compt.  rend.,  144,  825  (1907). 


177  HYDROGENATIONS  IN  THE  GAS  PHASE  497 

496.  Amines.    Various  amines  hydrogenated  over  nickel  at  above 
300-350°,  tend  to  form  ammonia  and  a  hydrocarbon.    This  reaction 
which  takes  place  readily  with  aliphatic  amines  has  already  been 
mentioned  with  aniline  (378).    It  takes  place  with  the  homologs  of 
aniline,  with  benzyl-amine  and  with  the  naphthyl-amines. 

Hexamethylene-tetramine  is  completely  decomposed  yielding 
ammonia,  trimethyl-amine  and  methane:131 

N(CH2  .  N  :  CH2)3  +  9H2  =  N(CH3)S  +  3NH3  +  3CH4. 

497.  Compounds  Containing  -N  .  N-.    Phenylhydrazine,  hydro- 
genated above  210°,  is  split  into  ammonia  and  aniline,  accompanied 
by  cyclohexyl-amine,  dicyclohexyl-amine,  and  even  by  benzene  and 
cyclohexane.132 

The  main  reaction  is: 

C6H5  .  NH  .  NH2  +  H2  =  NH3  +  C6H6  .  NH2. 

Azobenzene,  C6H5  .  N  :  N  .  C6H5,  hydrogenated  at  290°,  yields 
aniline  chiefly.132 

Indol.  On  hydrogenation  over  nickel  at  200°,  indol  is  split  into 
o.toluidine  and  methane:  133 


C6H  ;CH  +  3H2  =  CeH  +  CH4 

\NH/  \NH2 

181  GRASSI,  Gaz.  Chim.  Hal,  36  (2),  505  (1906). 

132  SABATIER  and  SBNDERBNS,  Bull  Soc.  Chim.  (3),  35,  259  (1906). 

133  CARRASCO  and  PADOA,  Lincei,  14  (2),  699  (1906),  C.,  1906  (2),  683. 


CHAPTER  X 

HYDROGENATIONS   (Continued) 

HYDROGEN ATIONS  IN  GASEOUS  SYSTEM  (Continued) 
I.  — USE  OF  VARIOUS  CATAUYSTS 

498.  Nickel  as  a  hydrogenation  catalyst  can  be  replaced  by  vari- 
ous finely  divided  metals,  such  as  cobalt,  iron,  copper,  platinum,  and 
the  platinum  metals,  particularly  palladium. 

Cobalt 

499.  Finely  divided  cobalt  such  as  is  produced  by  the  reduction 
of  the  oxide  in  the  hydrogenation  tube  itself,  seems  to  be  able  to  take 
the  place  of  nickel  in  all  the  various  reactions  which  nickel  can 
catalyze. 

But  its  use  is  disadvantageous  because  its  activity  is  less  and  more 
easily  destroyed  than  that  of  nickel;  because  higher  temperatures 
are  required  when  using  it ;  and  also  because  the  reduction  of  its  oxide 
is  practicable  only  in  the  neighborhood  of  400°,  and  hence  the  oxide 
resulting  from  spontaneous  oxidation  during  the  time  the  apparatus 
is  cold  and  out  of  use,  can  not  be  reduced  at  temperatures  below  250° 
such  as  are  commonly  used  in  hydrogenations. 

500.  Ethylene  Hydrocarbons.    When  a  mixture  of  ethylene  and 
an  excess  of  hydrogen  is  passed  over  cold  reduced  cobalt,  immediate 
action  takes  place  with  the  production  of  ethane,  and  the  end  of  the 
cobalt  layer  becomes  hot.    The  heated  portion  moves  slowly  along 
the  metal  and  the  evolution  of  heat  finally  ceases  and  the  production 
of  ethane  stops  also,  doubtless  because  the  cobalt  is  slightly  car- 
bonized in  the  course  of  the  reaction  and  its  activity  so  diminished 
that  it  is  unable  to  continue  the  reaction  without  the  aid  of  external 
heat. 

At  150°,  the  hydrogenation  of  ethylene  continues  indefinitely, 
but  the  cobalt  is  slowly  weakened,  more  rapidly  than  nickel. 

Above  300°,  the  disturbance  due  to,  the  action  of  the  cobalt  on 
the  ethylene  (910)  appears  and  the  issuing  gases  contain  methane 
and  carry  along  small  amounts  of  liquid  hydrocarbons.1 

1  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  344  (1905). 

178 


179  HYDROGENATIONS  IN  GASEOUS  SYSTEM  505 

The  action  of  cobalt  on  the  homologs  of  ethylene  is  similar  to 
that  of  nickel  but  weaker. 

501.  Acetylene.    Reduced  cobalt,  entirely  free  from  nickel,  can 
serve  to  hydrogenate  acetylene,  but  there  is  no  reaction  in  the  cold. 
The  fixation  of  hydrogen  begins  at  about  180°,  and  the  ethane  pro- 
duced is  accompanied  by  a  small  amount  of  liquid  hydrocarbons, 
which  are  more  abundant  if  the  reaction  is  carried  on  at  250°. 2 

502.  Benzene  and  its  Homologs.    Reduced  cobalt  can  effect  the 
direct  hydrogenation  of  benzene  and  its  homologs  at  180°,  but  its 
activity  falls  off  rather  rapidly.3 

503.  Aliphatic  Aldehydes  and  Ketones.    Cobalt  can  transform 
aliphatic  aldehydes  and  ketones  into  the  alcohols  below  180°,  but  is 
less  active  than  nickel.    Under  identical  conditions,  with  the  same 
apparatus,  the  same  temperature,  the  same  velocity  of  hydrogen,  and 
the  same  rate  of  admission  of  acetone,  the^yield  of  isopropyl  alcohol 
was  about  83%  with  nickel  as  catalyst  but  slightly  less  than  50% 
with  cobalt.4 

504.  Carbon  Monoxide  and  Dioxide.    Reduced  cobalt  can  cause 
the  transformation  of  carbon  monoxide  into  methane,  as  does  nickel, 
but  the  reaction  does  not  begin  till  about  270°.    It  is  rapid  at  300°, 
but  is  opposed  more  strongly,  than  is  the  case  with  nickel,  by  the 
decomposition  of  carbon  monoxide  into  carbon  and  the  dioxide  (615) . 
This  decomposition  is  as  rapid  with  cobalt  as  with  nickel,  while  the 
hydrogenation  is  slower  with  the  cobalt. 

The  hydrogenation  of  carbon  dioxide  is  effected  by  cobalt  from 
300°  up.  It  is  rapid  at  360°  and  even  more  so  at  400°  and  is  accom- 
plished without  any  complications.5 

Iron 

505.  Finely  divided  iron,  obtained  by  the  reduction  of  its  oxides, 
can  be  substituted  for  nickel  as  a  hydrogenation  catalyst  in  certain 
cases,  but  is  less  active  than  nickel  and  even  less  active  than  cobalt. 
Besides,  it  has  the  marked  disadvantage  of  being  much  more  difficult 
to  prepare  from  its  oxide.    Between  400  and  500°  it  is  necessary  to 
continue  the  action  of  hydrogen  from  six  to  seven  hours  to  obtain 
complete  reduction.    When  the  metal  is  reduced  more  rapidly  at 
higher  temperatures,  it  is  no  longer  pyrophoric  and  has  only  slight 
activity. 

2  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.    (8),  4,  352  (1905). 

8  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  368  (1905). 

4  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  400  and  403  (1905). 

6  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  424  (1905). 


606  CATALYSIS  IN  ORGANIC  CHEMISTRY  180 

506.  Ethylene   Hydrocarbons.    Iron   causes  the   hydrogenation 
of  ethylene  only  above  180°,  and  its  activity  decreases  with  the  slow 
carbonizing  of  the  metal. 

Acetylene.  The  hydrogenation  of  acetylene  does  not  commence 
till  above  180°,  and  always  gives  rise  to  the  formation  of  rather  large 
amounts  of  colored  hydrocarbons,  containing  higher  ethylene  hydro- 
carbons soluble  in  sulphuric  acid,  aromatic  hydrocarbons,  and  only 
a  small  amount  of  saturated  hydrocarbons.  The  odor  and  appearance 
of  the  product  suggest  certain  natural  petroleums  of  Canada. 

To  a  certain  extent,  iron  can  cause  the  hydrogenation  of  aldehydes, 
ketones  and  nitro  compoundsr  but  is  incapable  of  transforming  carbon 
monoxide  and  dioxide  into  methane  or  of  adding  hydrogen  to  the 
benzene  nucleus.6 

Copper 

507.  Reduced  copper  is  a  useful  catalyst  for  certain  hydrogena- 
tions.    For  such  its  use  is  advantageous  on  account  of  its  ease  of 
preparation,  the  low  temperature,  below  180°,  at  which  its  oxide  can 
be  reduced,  and  its  resistance  to  poisons  which  is  more  marked  than 
with  other  metal  catalysts. 

508.  Reduction  of  Carbon  Dioxide.     Copper,  even  in  its  most 
active  form  (59),  is  incapable  of  causing  the  direct  hydrogenation  of 
carbon  monoxide  to  methane  and  does  not  show  any  action  on  mix- 
tures of  carbon  monoxide  and  hydrogen  below  450°. 

It  is  the  same  way  with  mixtures  of  hydrogen  and  carbon  dioxide 
below  300° ,  but  between  350  and  400°  a  special  reaction  appears 
gradually  and  is  quite  definite  at  420-450°.  There  is  reduction  of 
the  carbon  dioxide  into  carbon  monoxide  and  water,  according  to  the 
equation: 

C0,2  +  H2  =  CO  +  H20. 

Thus  with  a  mixture  of  one  part  carbon  dioxide  to  about  three 
parts  of  hydrogen,  a  gas  was  obtained  containing: 

Carbon  monoxide  10.0%  by  volume 

Carbon  dioxide    17.2%    " 

Hydrogen    72.8%    " 

More  than  a  third  of  the  carbon  dioxide  had  been  reduced  to  the 
monoxide.  The  proportion  reduced  is  less  when  the  concentration  of 
hydrogen  in  the  mixture  is  less. 

•  SABATIER  and  SENDEBENS.  Ann.  Chim.  Phys.  (8),  4,  345,  353,  368,  425,  and 
428  (1905). 


181  HYDROGENATIONS  IN  GASEOUS  SYSTEM  512 

In  no  case  is  even  a  trace  of  methane  formed.7 

509.  Nitro  Compounds.     Copper  gives  results  analogous  to  those 
with  nickel  (373  to  378)  only  at  higher  temperatures. 

Nitrous  oxide  is  reduced  to  nitrogen  at  180°  and  nitric  oxide 
is  changed  into  ammonia  at  the  same  temperature.  Nitrogen 
peroxide  givies  copper  nitride  in  the  cold,8  and  it  is  only  towards 
180°  that  ammonia  is  produced.  If  the  proportion  of  nitrogen  per- 
oxide becomes  too  great,  there  is  incandescence  followed  by  an  ex- 
plosion.9 

510.  Nitromethane,  hydrogenated  between  300  and  400°,  gives, 
along  with  methyl-amine,  a  liquid  of  a  more  or  less  brown  color  with 
a  disgusting  odor  in  which  appear  crystals  which  are  the  methyl- 
amine -salt  of  nitromethane. 

Between  300  and  400°,  nitro-ethane  gives  ethyl-amine  without 
notable  complications.10 

511.  Copper  is  the  best  of  all  the  finely  divided  metals  for  trans- 
forming aromatic  nitro  derivatives  into  the  amines,  since  its  very 
regular  hydrogenating  action  affects  only  the  -NO2  group  and  does 
not  touch  the  aromatic  nucleus.    Nitrobenzene  is  thus  changed  to 
aniline  from  230°  up,  the  reaction  being  rapid  and  very  regular  be- 
tween 300  and  400°,  and  so  long  as  the  hydrogen  is  in  excess,  aniline 
is  obtained  in  98%  yield  containing  only  traces  of  nitrobenzene  and 
the  red  azobenzene.    The  same  metal  can  be  used  for  a  long  time. 
The  hydrogen  can,  without  inconvenience,  be  replaced  by  water  gas, 
the  carbon  monoxide  of  which  acts  usefully  as  a  reducing  agent  to 
some  extent  since  a  part  of  it  is  transformed  into  carbon  dioxide. 
The  manufacture  carried  out  with  copper,  a  metal  which  is  not  costly 
and  which  serves  for  a  long  time  and  is  easily  regenerated  without 
loss,  and  by  means  of  a  very  cheap  gas,  can  be  carried  on  continu- 
ously and  is  very  economical.11 

Coppered  pumice  at  200-210°  has  been  proposed  as  a  substitute 
for  copper.12 

512.  The  manufacture  of  the  toluidines  from  the  nitrotoluenes  is 
also  advantageously  carried  on  by  copper  at  300-400°,  and  likewise 

7  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  426  (1905). 

8  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (7),  7,  401  (1896). 

9  SABATIER  and  SENDERENS,  Compt.  rend.,  135,  278  (1902). 

10  SABATIER  and  SENDERENS,  Compt.  rend.,  135,  227  (1902). 

11  SABATIER  and  SENDERENS,  Compt.  rend.,  133,  321  (1901).  —  SABATIER,  Vth. 
Cong.  Pure  and  Appl.  Chem.,  Berlin,  1903,  II,  617.  —  SENDERENS,  French  Patent, 
312,615  (1901). 

12  BADISCHE,    English   patent.  6,409  of  1915.  —  J.  Soc.  Chem.  Ind.,  35,  920 
(1916). 


513  CATALYSIS  IN  ORGANIC  CHEMISTRY  182 

a-naphthyl-armne  is  readily  obtained  from  a-nitronaphthalene  at 
330-350°. 13 

The  chlornitrobenzenes  are  regularly  transformed  by  copper  into 
the  chloranilines  at  360-380°.  On  the  contrary,  copper  gives  poor 
results  with  the  dinitrobenzenes  and  the  bromnitrobenzenes.1* 

At  265°  the  results  are  excellent  with  the  nitrophenols  and  the 
nitranilines™ 

513.  Esters    of    Nitrous    Acid.    Nitrous    esters    are    regularly 
hydrogenated  into  the  amines,  over  copper  as  well  as  over  nickel,  but 
at  a  higher  temperature,  330-350°,  the  results  are  satisfactory  for 
nitrites  with  heavy  hydrocarbon  chains,  but  are  less  so  for  methyl 
nitrite  which  gives  brown  products  analogous  to  those  obtained  from 
nitromethane.16 

514.  Oximes.    Copper  accomplishes  the  regular  hydrogenation  of 
aliphatic  aldoximes  and  ketoximes  between  200  and  300°  into  primary 
and  secondary  amines  without  complications,17  and  the  same  may  be 
said  about  aliphatic  amides.™ 

515.  Ethylene  Compounds.    Most  often  copper  serves  to  add 
hydrogen  to  the  ethylene  double  bond. 

Ethylene,  propylene  and  a-octene  are  changed  to  the  correspond- 
ing saturated  compounds  at  above  180°.  However,  trimethyl- 
ethylene  and  /3-hexene  are  not  hydrogenated  by  copper,  and  it  has 
been  concluded  that  copper  does  not  cause  the  hydrogenation  of  any 
except  a  -ethylene  compounds,  that  is  to  say,  those  in  which  one  of 
the  CH2  groups  of  the  ethylene  is  not  substituted.19 

This  limitation  is  not  general  since  the  vapors  of  oleic  acid  are 
readily  hydrogenated  into  stearic  acid  at  around  300°.  Water  gas 
can  be  substituted  for  the  pure  hydrogen  in  this  preparation  and  it 
has  industrial  possibilities.20 

It  may  be  noted  that  copper  does  not  cause  the  hydrogenation  of 
symmetrical  diphenyl-ethylene,  or  stilbene,  C6H5 .  CH  :  CH  .  C6H5,  of 
cyclohexene,  C6H10,  or  of  the  methyl-cyclohexenes.21 

516.  The  use  of  copper,  which  acts  on  the  ethylene  double  bond 

18  SABATIER  and  SENDERENS,  Compt.  rend.,  135,  225  (1902). 

14  MIGNONAC,  Bull.  Soc.  Chim.,  (4),  7,  154,  270  and  504  (1910). 

16  BROWN  and  CARRICK,  J.  Amer.  Chem.  Soc.,  41,  436  (1919). 
18  GATTDION,  Ann.  Chim.  Phys.  (8),  25,  136  (1912). 

17  MAILHE,  Compt.  rend.,  140,  1691  (1905)  and  141,  113  (1905). 

18  MAILHE,  Bull.  Soc.  Chim.  (3),  35,  614  (1906). 

19  SABATIER  and  SENDERENS,  Compt.  rend.,  134,  1127  (1902). 

20  SABATIER,  French  patent,  394,957  (1907). 

21  SABATIER,  50th.  Cong,  des  Soc.  Sav.  (1912).    Journ.   Offic.,  3628:  April  11, 
1912. 


183  HYDROGENATIONS  IN  GASEOUS  SYSTEM  621 

without  attacking  the  aromatic  nucleus,  permits  us  to  effect  certain 
hydrogenations  distinct  from  those  obtained  with  nickel.  Phenyl- 
ethylene,  or  styrene,  C6H3  .  CH  :  CH2,  which  nickel  changes  into 
ethyl-cyclohexane,  is  transformed  quantitatively  at  180°  by  copper 
into  ethyl-benzene.22 


517.  Limonene,      CH8.C6H8.C'  which     nickel     readily 


changes  into  menthane   (477),  gives  only  dihydrolimonene,  C10H18, 
isomeric  with  menthene22 

518.  Acetylene    Hydrocarbons.     Copper    can    not    hydrogenate 
acetylene  in  the  cold,  the  reaction  being  around  130°  over  copper 
with  a  light  purple  color  and  around  180°  over  copper  of  a  clear  red. 
Carried  on  with  excess  of  hydrogen,  the  reaction  always  gives  a  cer- 
tain proportion  of  liquid  hydrocarbons  along  with  the  ethane. 

When  the  amount  of  acetylene  equals  or  surpasses  the  amount  of 
hydrogen,  the  special  condensing  action  of  copper  on  acetylene  (914) 
becomes  evident:  the  copper  swells  up  gradually  on  account  of 
the  formation  of  solid  cuprene,  (C7Hfl)x  the  gases  evolved  contain 
higher  ethylene  hydrocarbons  and  a  mixture  of  liquid  ethylene  and 
aromatic  hydrocarbons  (benzene,  and  homologs  and  styrene)  is  col- 
lected. 

A  gas  mixture  containing  21  H2  to  19  C2H,2  gave,  at  150°  over 
violet  copper,  a  condensation  of  materials  containing  25  C  with  about 
65%  carbon,  one  third  as  cuprene  and  the  other  two  thirds  as  liquid 
hydrocarbons.23 

519.  The  hydrogenation  of  a-heptine  over  copper  at  below  200°, 
gave  a  little  heptane,  but  chiefly  heptene,  diheptene,  and  triheptene2* 

520.  Phenyl  acetylene,  C6H5  .  C  ;  CH,   which  nickel   transforms 
easily  into  ethyl-cyclohexane    (451),   gave  by  hydrogenation  over 
copper    between    190    and    250°,    ethyl-benzene,    C6H6  .  CH2  .  CH3, 
accompanied  by  a  little  phenyl-ethylene  and  a  nearly  equal  amount 
of  symmetrical  diphenyl-butane,  C0H5  .  CH2  .  CH2  .  CH2  .  CH2  .  C6H6, 
a  well  crystallized  solid.25 

521.  Nitriles.    Copper  can  transform  nitriles  into  primary  and 
secondary  amines  26  in  the  same  manner  that  nickel  does.    It  acts 

22  SABATIEB  and  SENDERENS,  Compt.  rend.,  132,  1255  (1901). 

23  SABATIER  and  SENDERENS,  Compt.  rend.,  130,  1559  (1900). 

24  SABATIER  and  SENDERENS,  Compt.  rend.,  135,  87  (1902). 
26  SABATIER  and  SENDERENS,  Compt.  rend.,  135,  88  (1902). 

26  SABATIER  and  SENDERENS,  Compt.  rend.,   140,  482  (1905)   and  Bull.  Soc. 
Chim.  (3),  33,  371  (1905), 


522  CATALYSIS  IN  ORGANIC  CHEMISTRY  184 

similarly  on  the  carbyl-amines?7  but  its  action  is  less  rapid  than  that 
of  nickel. 

522.  Aliphatic   Aldehydes   and   Ketones.    Below  200°,   copper 
can  transform  these  slowly  into  the  alcohols,  but  the  inverse  action 
usually    preponderates    and    this    makes    the    use    of    copper    less 
advantageous. 

Furthermore,  copper  is  incapable  of  transforming  the  oxides  of 
carbon  into  methane  or  of  hydrogenating  the  aromatic  nucleus. 

523.  Aromatic   Ketones.    When   benzophenone   is   hydrogenated 
at  350°  over  copper  with  a  violet  tint,  prepared  by  the  reduction  of 
the  hydroxide   (59),  diphenyl-methane  is  formed  directly.28 

Platinum 

524.  Platinum  black  can  be  used  for  direct  hydro genation  in  quite 
a  large  number  of  cases  and  its  activity  is  greater  than  that  of  copper 
though  less  than  that  of  nickel.    Its  activity  is  greater,  the  more 
tenuous  the  black  and  the  more  recently  it  has  been  prepared.     It  is 
rapidly  exhausted  and  this  fact  taken  together  with  the  high  cost  of 
the  metal  renders  its  use  generally  less  advantageous. 

Platinum  moss,  or  sponge,  behaves  the  same  way  but  with  less 
activity,  which  is  usually  not  manifested  except  at  a  higher  tempera- 
ture. 

525.  Union  of  Carbon  and  Hydrogen.     The  presence  of  finely 
divided  platinum  on  the  carbon  accelerates  its  direct  combination 
with  hydrogen  to  form  methane  at  1200°,  the  limit  of  the  combina- 
tion, 0.53%,  not  being  altered.29 

526.  Ethylene  Compounds.    A  mixture  of  ethylene  and  hydrogen 
is  transformed  into  ethane  in  the  cold  in  the  presence  of  platinum 
black.30    But  after  some  time  the  slight  carbonization  of  the  metal 
prevents  the  reaction  from  proceeding  at  the  ordinary  temperature 
and  it  is  necessary  to  heat  to  120°,  or  even  to  180°,  to  obtain  a  rapid 
formation  of  ethane.81 

Analogous  results  are  obtained  with  propylene. 
The  vapors  of  amyl  oleate  can  be  hydrogenated  over  platinized 
asbestos  to  amyl  stearate.*2 

527.  Acetylene  Hydrocarbons.    Acetylene  combines  with  hydro- 

"  SABATIEB  and  MAILHB,  Ann.  Chim.  Phys.,  (8)  16,  95  (1909). 
88  SABATIEB  and  MURAT,  Campt.  rend.,  158,  761  (1914). 
M  PRING,  J.  Chem.  Soc.,  97,  498  (1910). 

80  VON  WILDE,  Berichte,  7,  352  (1874). 

81  SABATIER  and  SENDERENS,  Compt.  rend.,  131,  40  (1900). 

82  FOKIN,  J.  Russian  Phys.  Chem.  Soc.,  38,  419  (1906),  C.,  1906  (2),  758. 


185  HYDROGENATIONS  IN  GASEOUS  SYSTEM  533 

gen  in  the  cold  in  the  presence  of  platinum  black,  giving  first  ethylene 
and  then  ethane.30 

In  presence  of  an  excess  of  hydrogen,  acetylene  is  entirely  trans- 
formed into  pure  ethane  without  any  side  reactions. 

At  180°  the  same  reaction  takes  place  more  rapidly  but  there  is 
the  formation  of  a  certain  amount  of  higher  liquid  hydrocarbons. 
By  augmenting  the  proportion  of  acetylene  in  the  mixture,  ethylene 
becomes  the  main  product  but  some  ethane  is  always  formed  even 
though  unchanged  acetylene  remains. 

If  the  proportion  of  acetylene  becomes  great  enough,  with  the 
platinum  black  at  180°,  a  certain  amount  of  smoky  decomposition 
of  the  gas  is  observed  and  this  ends  with  incandescence,  as  is  the  case 
with  nickel  (914) . 

Platinum  sponge  is  not  active  in  the  cold  and  does  not  effect  the 
hydrogenation  of  acetylene  except  above  ISO0.33 

528.  Hydrocyanic     Acid.     Platinum     black     can    hydrogenate 
hydrocyanic  acid  to  methyl-amine  at  116°,  but  the  cyanidation  of  the 
metal  soon  diminishes  its  activity  and  stops  the  reaction.34 

529.  Nitro  Compounds.    Nitrogen  oxides,  either  nitric  oxide  or 
the  dioxide,  are  readily  reduced  to  ammonia  with  the  aid  of  platinum 
sponge  which  is  thereby  heated  to  incandescence.35 

530.  Nitromethane  is  hydrogenated  over  platinum  sponge  at  300°, 
more  slowly  than  over  copper  but  with  analogous  results  (510)  ,86 

531.  Various  forms  of  platinum,  black,   sponge,   and  platinized 
asbestos,  can  cause  the  transformation  of  nitrobenzene  into  aniline, 
but  their  catalytic  power  is  low  and,  if  the  hydrogen  is  not  in  large 
excess,  there  is  incomplete  reduction  with  the  formation  of  crystal- 
lized hydrazobenzene.37 

532.  Aliphatic  Aldehydes  and  Ketones.    Finely  divided  plati- 
num is  unsuitable  for  the  regular  transformation  of  these  into  the 
alcohols,  since  at  the  temperatures  which  must  be  used,  which  are 
above  200°,  the  metal  acts  powerfully  to  break  up  the  aldehyde  mole- 
cule into  carbon  monoxide  and  hydrocarbon  (622). 

533.  Finely  divided  platinum,  even  in  the  form  of  highly  active 
black,  has  proved  powerless  to  effect  the  direct  hydrogenation  of 
carbon  monoxide  or  dioxide  to  methane.    There  is  no  action  even  up 
to  450°. 38 

88  SABATIER  and  SENDERENS,  Compt.  rend.,  131,  40  (1900). 

84  DEBUS,  J.  Chem.  Soc.,  16,  249  (1863). 

36  KUHLMANN,  Compt.  rend.,  7,  1107  (1838). 

36  SABATIER  and  SENDERENS,  Compt.  rend.,  135,  226  (1902). 

87  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  414  (1905). 

88  SABATIER  and  SENDERENS,  Compt.  rend.,  134,  514  and  689  (1902). 


534  CATALYSIS  IN  ORGANIC  CHEMISTRY  186 

534.  Aromatic  Nucleus.    Recently  prepared  platinum  black  can 
transform  benzene  into  cyclohexane  at  180°  for  a  time,  but  its  ac- 
tivity diminishes  rapidly  and  soon  disappears. 

Platinum  sponge  has  not  this  power.39 

According  to  Zelinsky,  platinum  is  as  well  able  to  hydrogenate 
benzene,  toluene,  the  three  xylenes  and  ethyl-benzene,  as  is  nickel.40 
He  states  the  same  about  palladium. 

535.  Polymethylene  Rings.    Spirocyclane,  with  the  aid  of  plati- 
num, first  adds  H2  to  form  ethyl  trimethylene,  which  passes  to  pen- 
tane  by  a  second  addition:  41 


CH 

V  —  x 

\CH2      CH2/ 


Cyclo-octatetrene  adds  4H2  with  the  aid  of  platinum  sponge  to 
form  cyclooctane.42 

Palladium 

536.  Palladium,  previously  charged  with  hydrogen,  is  able  to  effect 
varied  hydrogenations,  such  as  the  transformation  of  nitrobenzene  into 
aniline,  nitromethane  into  methyl-amine,  and  nitrophenols  into  amino- 
phenols  (Graham)  .  It  is  easy  to  foresee  that  it  can  serve  equally  well 
as  a  hydrogenation  catalyst,  the  intermediate  hydride  which  enables 
it  to  accomplish  these  results  being  notably  stable  in  this  case. 

The  formation  of  aniline  by  the  action  of  hydrogen  on  nitrobenzene 
in  the  presence  of  palladium  was  shown  by  Saytzeff.43 

Carbon  monoxide  can  be  reduced  in  the  cold,  or  better,  at  400°, 
to  methane  in  the  presence  of  palladium  sponge.44 

Phenanthrene,  carried  over  palladium  sponge  at  150-160°  by  a 
current  of  hydrogen,  gives  a  mixture  of  tetrahydro-  and  octohydro- 
phenanthrene*5 

Unfortunately  the  excessive  price  of  palladium  restricts  its  useful 
applications. 

39  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  368  (1905). 

40  ZELINBKY,  /.  Russian  Phys.  Chem.  Soc.,  44,  274  (1912). 

41  ZELINSKY,  J.  Russian  Phys.  Chem.  Soc.,  44,  275  (1912). 

42  WILLSTATTEB  and  WASER,  Berichte,  44,  3423  (1911). 

48  KOLBE  and  SAYTZEFF,  J.  prakt.  Chem.  (2),  4,  418  (1871). 

44  BRETEATJ,  Etude  sur  les  meth.  d'  hydrogenation,  1911,  p.  22. 

45  BRETEAU,  Ibid.,  p.  24. 


187  HYDROGENATIONS  IN  GASEOUS  SYSTEM  538 

II.  — HYDROGENATION  BY  NASCENT  HYDROGEN 

537.  Certain  catalyses  yield  hydrogen  and  the  gas  so  produced 
can  be  immediately  employed  for  hydrogenation  purposes.    We  can 
thus  use  as  sources  of  active  hydrogen,  alcohol  vapors,  formic  acid, 
and  even  a  mixture  of  water  and  carbon  monoxide. 

Hydrogenation  by  Alcohol  Vapors 

538.  Primary  and  secondary  alcohols  can,  under  the  influence  of 
various  catalysts,  be  decomposed  into  aldehydes  and  ketones  and 
hydrogen  (653) :    the  hydrogen  thus  set  free  can  act  in  the  nascent 
state  on  substances  the  vapors  of  which  are  mixed  with  the  alcohols. 

Copper  can  easily  realize  such  reactions,  but  we  can  attribute  to 
its  action  the  hydrogenation  correlative  to  the  decomposition. 

We  can  use  mixed  oxide  catalysts  (675)  and  even  dehydrating 
catalysts,  such  as  thoria,  the  presence  of  the  substance  that  can  be 
hydrogenated  orienting  the  decomposition  of  the  alcohol  in  the  direc- 
tion of  the  separation  of  hydrogen  and  greatly  diminishing  the  extent 
of  the  dehydration  reaction. 

Thus  over  thoria  at  420°,  benzhydrol,  with  ethyl  alcohol  in  excess, 
gives  much  diphenyl-methane  accompanied  by  a  little  benzophenone 
and  tetraphenyl-ethane  (720) :  acetaldehyde  is  evolved  and  the  gases 
arising  from  its  decomposition. 

The  alcohol  most  suitable  for  this  sort  of  hydrogenation  is  methyl 
alcohol  on  account  of  its  great  tendency  to  produce  formaldehyde 
and  particularly  the  products  of  its  decomposition,  carbon  monoxide 
and  hydrogen  (693) : 

H  .  CH2OH  =  2H2  +  CO. 

The  vapors  of  the  substance  to  be  hydrogenated  are  passed  over 
thoria  at  420°,  with  an  excess  of  methyl  alcohol,  the  hydrogenation 
is  advantageously  accomplished  in  all  cases  in  which  the  product  is 
stable  at  that  temperature.  Thus  benzophenone  and  benzhydrol  are 
changed  almost  completely  into  diphenyl-methane ,  while  benzyl  al- 
cohol and  benzaldehyde  give  toluene,  acetophenone  furnishes  ethyl- 
benzene,  and  nitrobenzene  yields  aniline*6  *7 

46  SABATIER  and  MURAT,  Compt.  rend.,  157,  1499  (1913).  —  Butt.  Soc.  Chim. 
(4),   15,  227  (1914). 

47  By  using  2.5  moles  of  ethyl  alcohol  to  1  of  benzaldehyde,  and  passing  the 
mixed  vapors  over  ceria  on  asbestos  at  300-300°,  benzyl  alcohol  is  obtained 
along  with  acetaldehyde.     Similarly  citronellol  is  formed  from  citronellal  and 
phenylethyl  alcohol  from  phenylacetaldehyde.     The  yields  are  variable  and  the 
catalyst  is  rapidly  fouled,  probably  on  account  of  the  formation  of  condensation 
products   of   the  aldehydes  either  alone  or  with   each  other.     See    article   by 
Milligan  and>yself,  Jour.  Amer,  Chem.  Soc.,  44,  202  (1922).  — E.  E.  R. 


539  CATALYSIS  IN  ORGANIC  CHEMISTRY  188 

Hydrogenation  by  the  Vapors  of  Formic  Acid 

539.  The  vapors  of  formic  acid  passing  over  various  catalysts, 
finely  divided  platinum,  copper  or  nickel  reduced  from  their  oxides, 
cadmium,  stannous  oxide  or  zinc  oxide,  are  decomposed  below  300° 
into  carbon  dioxide  and  hydrogen  (824) : 

HC02H  =  H2  +  C02. 

This  hydrogen  can  be  used  to  hydrogenate  substances  the  vapors 
of  which  are  present  in  the  system.  Under  these  conditions,  using 
nickel  at  300°,  acetophenone  is  changed  to  ethyl-benzene,  phenyl- 
ethyl-ketone  into  propyl-benzene,  and  benzophenone  into  diphenyl- 
me  thane. 

Thoria,  alumina  and  zirconia  effect  the  same  hydrogenations  above 
300°,  but  the  oxides  of  manganese  appear  to  be  inactive.48 

Hydrogenation  by  the  Mixture  of  Carbon  Monoxide  and  Water 

540.  The  mixture  CO  +  H20  can  be  transformed  into  C02  +  H2, 
the  reaction  being  favored  by  the  temporary  combination  of  the  car- 
bon dioxide  with  the  catalyst  or  by  the  immediate  utilization,  thanks 
to  the  catalyst,  of  the  hydrogen  to  hydrogenate  the  carbon  monoxide 
into  methane.    The  reaction  then  becomes: 

4CO  +  2H20  =  3C02  +  CH4. 

It  is  found,  in  fact,  that  a  mixture  of  steam  and  carbon  monoxide 
passing  over  lime  at  above  1000°  gives  the  above  reaction  and  we 
have  the  following  reaction  at  the  same  time: 

CO  +  H20  =  C02  +  H2. 

As  calcium  carbonate  is  entirely  decomposed  at  this  temperature, 
the  lime  acts  as  a  true  catalyst.  By  separating  the  carbon  dioxide, 
we  can  obtain  a  mixture  containing: 

Hydrogen    88%  by  volume 

Methane 49    12% 

The  same  mixture  passing  over  iron  wool  likewise  gives  methane 
in  varying  amounts: 

At    250° 7.3%  by  volume 

At    950°    11.2% 

At  1250°    7.1% 

By  the  use  of  fine  nickel  turnings  a  maximum  content  of  12.5%  of 

48  MAILHE  and  DE  GODON,  Butt.  Soc.  Chim.  (4) ,'"21,  61  (1917). 

49  VIQNON,  Compt.,  rend.,  156,  1995  (1913). 


189  HYDROGENATIONS  IN  GASEOUS  SYSTEM  640 

methane  is  obtained  at  400°.    With  copper  turnings,  almost  no  result 
is  obtained  at  500°,  and  the  maximum,  6.3%,  is  obtained  at  700°. 

Precipitated  silica  gives  a  maximum  of  8.4%  at  700°,  while  for 
alumina,  obtained  by  calcining  the  hydroxide,  the  maximum,  3.8%, 
is  obtained  at  950 °,  and  for  magnesia,  a  maximum  of  6.7%  at  900 °.50 

80  VIGNON,  Compt.  rend.,  157,  131  (1913).  —  Butt.  Soc.  Chim.  (4),  13,  889  (1913). 


CHAPTER  XI 
HYDROGENATIONS   (Continued) 

DIRECT  HYDROGENATIONS   OF  LIQUIDS   IN 
CONTACT   WITH  METAL   CATALYSTS 

541.  We  have  explained  the  phenomena  of  direct  hydrogenation 
as  accomplished  by  various  finely  divided  metals  when  the  substance 
to  be  hydrogenated  is  brought  in  contact  with  the  metal  in  the  gaseous 
form,  by  assuming  a  sort  of  hydride  of  the  metal,  an  unstable  com- 
pound formed  rapidly  and  decomposed  rapidly  in  the  act  of  hydro- 
genating  the  substance  (165).    This  explanation  does  not  necessarily 
require  that  the  substance  to  be  hydrogenated  be  in  the  gaseous  form 
as  we  can  see  that  the  same  reaction  can  be  accomplished  with  a 
liquid  material  intimately  mixed  with  a  finely  divided  metal  capable 
of  taking  up  hydrogen.    In  order  that  the  hydrogen  may  come  into 
contact  with  the  metal  it  is  necessary  that  its  solubility  in  the  liquid 
be  made  sufficiently  great  by  using  low  temperatures  at  the  ordinary 
pressure,  or  a  high  pressure  of  hydrogen  if  it  is  necessary  to  heat. 

An  energetic  and  continuous  agitation,  constantly  renewing  the 
contact  of  the  catalyst  with  the  unchanged  portions  of  the  liquid  will 
be  most  useful. 

Furthermore,  in  order  for  the  metal  to  be  able  to  preserve  its 
activity,  it  must  not  be  oxidisable  at  the  working  temperature,  or 
this  temperature  must  be  high  enough  to  assure  the  reduction  by  the 
hydrogen  in  the  system  of  any  oxide  formed. 

542.  From  these  conditions  may  be  derived  several  methods  which 
give  results  in  general  identical  with  those  obtained  by  the  method 
of  Sabatier  and  Senderens  of  hydrogenating  vapors  over  nickel,  and 
which  may  offer  great  advantages  in  some  cases. 

The  first  attempt  to  hydrogenate  substances  directly  in  the  liquid 
state  had  for  its  object  the  hydrogenation  of  liquid  fats  and  was  made 
in  1902-1903.1  Then  followed  the  method  of  Ipatief  based  on  the  use 
of  nickel  at  250  to  400°  in  the  presence  of  hydrogen  compressed  to 
more  than  100  atmospheres,  and  at  almost  the  same  time  the  method 

1  LEPKINCE  and  SIEVKE,  German  patent,  141,029  (1903).  —  NORMAN,  English 
patent,  1515  of  1903.     Chem.  Cent.,  1903  (1),  1199. 

190 


191  DIRECT  HYDROGENATIONS  OF  LIQUIDS  545 

of  Paal,  relying  on  the  use  of  colloidal  metals  (platinum  or  palladium) 
acting  at  near  the  ordinary  temperature,  and  then  in  1908,  the  method 
of  Willstatter  which  depends  on  the  use  of  platinum  black. 

We  shall  take  up  first  the  methods  using  the  precious  metals,  then 
those  employing  the  common  metals  whether  at  high  pressures  of 
hydrogen  or  at  pressures  near  the  atmospheric. 

543.  Except  the  process  of  Ipatief,  which,  on  account  of  the  high 
pressures  used,  demands  an  entirely  special  outfit,  the  various  methods 
of  hydrogenation  in  liquid  medium    employ  apparatus  of  the  same 
kind,  though  they  may  vary  much  in  forms  and  dimensions.    The 
main  thing  is  a  working  vessel  containing  the  liquid  to  be  hydro- 
genated,  either  alone  or  dissolved  in  a  suitable  solvent  and  mixed 
with  the  solid  catalyst.    This  recipient,  which  must  be  capable  of 
being  kept  at  known  temperatures,  is  mounted  on  a  mechanical  shaker 
capable  of  assuring  the  best  possible  contact  between  liquid,  catalyzer, 
and  hydrogen.    It  is  kept  in  communication  with  a  cylinder  of  com- 
pressed hydrogen  which  can  be  introduced  from  time  to  time  under 
known  pressures,  or  if  the  hydrogenation  is  to   be   carried  on   at 
atmospheric  pressure,  the  recipient  communicates  continuously  with 
a  hydrogen  gasometer,  the  graduations  of  which  enable  us  to  follow 
the  course  of  the  reaction  and  to  determine  its  end. 

I.  — METHOD  OF  PAAL 

544.  The  methods  of  preparing  colloidal  platinum  and  palladium, 
such  as  are  used  in  the  method  of  Paal,  have  been  given  above  (67  to 
71).    The  amounts  of  these  metals  to  be  used  are  not  over  16  to  50% 
of  the  weight  of  the  substance  to  be  hydrogenated,  and  can,  according 
to  Paal,  be  reduced  to  from  0.5  to  1%  for  colloidal  palladium  or  to 
1  to  2%  for  colloidal  platinum.2 

Use  of  Colloidal  Palladium 

545.  Reductions  with   Simultaneous   Fixation   of   Hydrogen. 

Nitro  compounds  are  readily  changed  into  amino  compounds.  Thus 
nitrobenzene  is  easily  transformed  into  aniline,  particularly  at  65- 
85°.8 

Nitroacetophenone  gives  aminoacetophenone.4 

The  halogen  of  chlorine  or  bromine  derivatives  may  be  readily 
replaced  by  hydrogen  when  a  current  of  hydrogen  is  passed  through 

2  PAAL,  German  patent,  298,193,  1913,  —  Chem.  Cent.,  1917  (2),  145. 

3  PAAL  and  AMBERQER,  Berichte,  38,  1406  (1906). 

4  SKITA  and  MEYER,  Berichte,  45,  3579  (1912). 


546  CATALYSIS  IN  ORGANIC  CHEMISTRY  192 

the  compound  containing  colloidal  palladium  and  boiling  under  reflux. 
Thus  we  obtain  benzene  from  brombenzene.  This  reduction  works 
well  with  o.chlor-benzoic  acid,  o.chlorcinnamic  acid,  chlorcrotonic 
acid,  and  chlor caffeine,  etc.,  without  any  other  change  in  the  mole- 
cule.5 

546.  Fixation  of  Hydrogen  by  Addition.  The  ethylene  double 
bond  is  readily  hydrogenated. 

Ethylene  is  easily  transformed  into  ethane.6 

Styrene  gives  ethyl-benzene. 

Bromstyrene  is  simultaneously  saturated  and  dehalogenated  to 
ethyl-benzene.7 

l,10-Diphenyl-decadiene(l$)   furnishes  1,10-diphenyl-decane* 

Mesityl  oxide,  treated  in  alcohol  solution  with  the  metal  prepared 
by  means  of  gum  arabic,  changes  into  methyl-isobutyl-ketone.9 

a-M  ethyl- fi-ethyl-propenal,  hydrogenated  under  the  same  condi- 
tions under  2  atmospheres  pressure  of  hydrogen,  gives  chiefly  the 
saturated  aldehyde,  a-methyl-valeric  aldehyde,  accompanied  by  a 
small  amount  of  the  unsaturated  alcohol  a-methyl-pentenyl  alcohol.10 

Crotonic,  isocrotonic,  and  tetrolic  acids  are  transformed  into  the 
corresponding  saturated  acids.11 

Fumaric  acid  in  an  hour  and  a  half,  and  maleic  acid  in  seven  hours 
are  changed  into  succinic  acid.  Oleic  acid  gives  a  60%  yield  of 
stearic  acid  in  43  minutes. 

Cinnamic  acid  is  changed  into  phenylpropionic  acid.12 

Cinnamic  aldehyde,  dissolved  in  20  parts  of  alcohol,  is  transformed 
into  phenylpropionic  aldehyde. ,18 

Isopropylidene-cyclopentanone  adds  H2  to  form  isopropyl-cyclo- 
pentanone: " 

CH3\  /CO  -CH2  CH3\  /CO-  CH2 

;C:C(  1          -j  ;CH.CH( 

CH3/         \CH2-CH2  CH3/  \CH2-CH2 

ROSENMUND  and  ZETSCHE,  Berichte,  51,  579  (1918). 
PAAL  and  HARTMANN,  Berichte,  48,  984  (1915). 
BOBSCHE  and  HEIMBIJRQER,  Berichte,  48,  452  (1915). 
BORSCHE  and  WOLLEMANN,  Berichte,  44,  3185  (1911). 

WALLACH,  Nach.  Ges.  der  Wiss.  Gottingen,  1910,  517.  —  SKITA,  Berichte,  48 
1486  (1915). 

10  SKITA,  Berichte,  48,  1486  (1915). 

11  BO"ESEKEN,  VAN  DER  WEIDE  and  MOM,  Rec.   Trav.  Chim.  Pays  Bos.,  35, 
260   (1915). 

12  PAAL  and  GERUM,  Berichte,  41,  2273  and  2277  (1908). 

18  SKITA,  Berichte,  48,  1691  (1915).  —  BOESEKEN,  VAN  DER  WEIDE  and  MOM, 
Rec.  Trav.  Chim.  Pays-Bas,  35,  260  (1916). 
14  WALLACH,  Annalen,  394,  362  (1912). 


193  DIRECT  HYDROGENATIONS  OF  LIQUIDS  548 

547.  In  the  case  of  diethylene  compounds,  if  the  double  bonds  are 
consecutive,  both  are  hydrogenated  simultaneously  but  if  they  are 
separated  by  more  than  one  carbon  atom,  they   are  hydrogenated 
successively. 

Thus  phorone  gives  first  dihydrophorone  and  then  valerone. 

Dibenzylidene-acetone,  C6H5 .  CH  :  CH  .  CO  .  CH  :  CH  .  C6H5,  can 
give  first  benzyl-benzylidene-acetone,  C6H5 .  CH  :  CH  .  CO  .  CH2  .- 
CH2 .  C6H5,  and  then  dibenzyl-acetone.15 

548.  The  acetylene  triple  bond  can  be  saturated  in  two  steps. 
Acetylene  itself  gives  ethylene  chiefly,  up  to  80%. 16 

Phenyl-acetylene  in  acetic  acid  solution  gives  styrene  and  then 
ethyl-benzene.17 

Tolane  yields  stilbene  and  then  dibenzyl.  Diphenyl-diacetylene 
passes  intoay-diphenyl-butadieneay,  then  into  cty-diphenyl-butane17 

Phenylpropiolic  acid,  C6H5 .  C  i  C  .  COOH,  gives  a  poor  yield  of 
cinnamic  acid,  C6H5 .  CH  :  CH .  C02H,  and  does  not  go  into  phenyl- 
propionic.18 

2,5-Dimethyl-hexine(3)-diol(2,5)  adds  only  H2  to  give  the 
ethylene-diol,  and  the  same  is  true  of  l,4^diphenyl-butine(2)- 
diol(l,4)  19  and  of  dimethyl-diethyl-butine-diol20  while  dimethyl- 
diphenyl-butine-diol  gives,  in  succession,  the  ethylene  glycol  and  the 
saturated  glycol.21  On  the  contrary,  2-methy1r-4r-phenyl-butine(3)~ 
61(2),  (CH3)2C(OH)  .  C  C  .  C6H5,  adds  2H2  immediately  to  give  the 
saturated  alcohol.22 

CH3.CH2\  /CH2.CH3 

Dimethyl-octine-diol,  /C(OH)  .C  i  C  .C(OH)(  , 

CH3/  \CH3 

hydrogenated  in  alcohol  solution,  adds  H2  to  form  dimethyl-octene- 
diol23 

In  the  hydrogenations  of  these  acetylene  glycols,  the  speed  of  the 
reaction  is  usually  proportional  to  the  amount  of  catalyst  present, 

16  PAAL,  Berichte,  45,  2221  (1912). 

16  PAAL  and  HOHENEGQER,  Berichte,  48,  275  (1915).  —  PAAL  and  SCHWARZ, 
Berichte,  48,  1202  (1915). 

17  KELBER  and  SCHWARZ,  Berichte,  45,  1951  (1912). 

18  PAAL  and  SCHWARZ,  Berichte,  51,  640  (1918). 

19  ZALKIND,  J.  Russian  Phys.  Chem.  Soc.,  45,  1875  (1914),  C.  A.,  8,  1419. 

20  ZALKIND  and    Miss    MARKARTAN,  J.  Russian  Phys.   Chem.  Soc.,  48,  538 
(1916),  C.  A.,  n,  584. 

21  ZALKIND  and  KVAPISHEVSKII,  /.  Russian  Phys.  Chem.  Soc.,  47,  688  (1915), 
C.  A.,  9,  2511. 

22  ZALKIND,  J.  Russian  Phys.  Chem.  Soc.,  47,  2045  (1915),  C.  A.,  10,  1355. 
28  ZALKIND  and  Miss  MARKARYAN,  /.  Russian  Phys.  Chem.  Soc.,  48,  538  (1916), 

C.  A.,  n,  584. 


549  CATALYSIS  IN  ORGANIC  CHEMISTRY  194 

but  sometimes  it  is  independent  of  the  amount  of  catalyst,  contrary 
to  all  predictions. 

549.  The  transformation  of  aldehydes  and  ketones  into  alcohols 
can  be  effected,  but  with  difficulty. 

Benzaldehyde  is  partially  reduced  to  benzyl  alcohol.2* 

Phenyl-acetaldehyde  is  regularly  hydrogenated  to  the  correspond- 
ing alcohol. 

With  hydrogen  at  one  atmosphere  pressure,  phorone  is  hydro- 
genated to  di-isobutyl-carbinol,  but  under  half  an  atmosphere,  the 
reduction  stops  at  valerone24 

In  acetic  acid  solution,  mesityl  oxide  is  hydrogenated  to  methyl- 
isobutyl-carbinol,  but  in  alcohol,  as  stated  above,  the  reaction  stops 
at  the  ketone.25  The  saturated  alcohol  is  also  obtained  by  working 
under  5  atmospheres  pressure.24 

550.  Hydroxy-methylene      derivatives      containing     the      group 
)C  :  CHOH,  are  changed  into  methyl  derivatives  \CH .  CH3. 26 

551.  Benzole  acid  furnishes  hexahydrobenzoic27 

552.  Carvone  is  transformed  into   tetrahydrocarvone.    There  is 
addition  of  hydrogen  to  the  double  bonds  of  pinene,  which,  under  2 
atmospheres  pressure,  gives  pinane,  of  camphene  which  passes  to 
camphane,  melting  at  53°,28  of  eucarvone,  of  a-  and  /3-terpineols,  of 
thujone,  of  isothujone,  of  methylheptenone,  of  cyclohexenone,  etc.29 
Likewise  pulegone  is  changed  to  menthone. 

553.  Naphthalene  is  reduced  to  decahydronaphthalene.30 

554.  Azobenzene,  in  alcohol  solution  under  2  atmospheres  pres- 
sure of  hydrogen,  is  reduced  to  hydrazobenzene  in  five  minutes  and 
then  into  aniline  in  4.5  hours.    Orange  No.  3  is  immediately  de- 
colorized under  these  conditions.30 

The  a-  and  /3-ionones  are  transformed  into  the  odorless  dihydro- 
and  then  into  the  tetrahydroionones.31 

555.  Quinidine  gives  dihydroquinidine,  melting  at  165°.       Cin- 
chonidine  adds  H2  to  form  the  dihydro-  melting  at  229 °.32     Cin- 
chonine  adds  H2  to  form  cinchotine33 

24  SKITA  and  RITTEB,  Berichte  43,  3393  (1910). 

*  SKITA,  Berichte,  48,  1486  (1915). 

28  KOTZ  and  SCHAEFFER,  J.  prakt.  Chem.  (2),  88,  604  (1913). 

27  SKITA  and  MEYER,  Berichte,  45,  3587  (1912). 

28  SKITA  and  MEYER,  Berichte,  45,  3579  (1912). 

29  WALLACE,  Annakn,  336,  37  (1904). 
"  SKITA,  Berichte,  45,  3312  (1912). 

81  SKITA,  MEYER  and  BERGEN,  Berichte,  45,  3312  (1912). 

82  SKITA  and  NORD,  Berichte,  45,  3316  (1912). 
»  PAAL,  German  patent,  223,413. 


195  DIRECT  HYDROGENATIONS  OF  LIQUIDS  659 

Pyridine  is  changed  to  piperidine  and  quinoline  to  decahydro- 
quinoline.27  Diacetyl-morphine  furnishes  the  dihydro-  and  pipeline, 
tetrahydropiperine.28 

Strychnine,  dissolved  in  dilute  nitric  acid  under  2  atmospheres 
pressure  of  hydrogen,  gives  the  dihydro-,  but  under  3  atmospheres, 
tetrahydrostrychnine,  while  brucine  always  gives  its  dihydro-.34 

Colchicine  furnishes  tetrahydrocolchicine.55 

Egg  lecithine,  dissolved  in  absolute  alcohol,  gives  hydrolecithine.™ 

Use  of  Colloidal  Platinum 

556.  Colloidal  platinum,  prepared  according  to  one  of  the  methods 
given  in  Chapter  II  (67  to  71),  can  be  substituted  for  colloidal  palla- 
dium and  gives  results  but  little  different. 

According  to  Paal  and  Gerum  its  activity  is  less.37  According  to 
Fokin,  on  the  contrary,  the  platinum  is  three  times  as  active  and  much 
more  apt  to  hydrogenate  the  aromatic  nucleus.38  The  velocity  of 
the  hydrogenation  increases  rapidly  with  the  amount  of  the  metal 
employed.39 

557.  The  reduction  of  m£ro-derivatives  into  amino-  is  readily  carried 
out  with  nitrobenzene  which  gives  aniline  and  with  nitroacetophenone 
which  yields  aminoacetophenone.40 

558.  The  addition  of  hydrogen  to  double  and  triple  bonds  takes 
place  easily  even  with  many  complex  rings. 

Ethylene  is  transformed  to  ethane  but  less  rapidly  than  by  colloidal 
palladium,  the  action  being  proportional  to  the  amount  of  platinum 
used.41 

Amylene  is  changed  to  pentane,  oleic  and  linoleic  acids  into  stearic 
and  crotonic,  maleic,  aconitic,  sorbic,  citraconic,  and  itaconic  acids  are 
changed  into  the  corresponding  saturated  acids,  while  allyl  alcohol  gives 
propyl  alcohol.39 

Acetylene  is  reduced  to  a  mixture  of  ethylene  and  ethane.42 

559.  Heptaldehyde,  hydrogenated  by  the  aid  of  colloidal  platinum 
prepared  by  the  germ  method,  is  changed  to  heptyl  alcohol.43 

84  SKITA  and  PAAL,  German  patent,  230,724,  C.,  1911  (1),  522. 

86  HOFFMANN  — LA  ROCHE  &  Co.,  German  patent,  279,999,  C.,  1914  (2), 1214. 

36  PAAL  and  OEHME,  Berichte,  46,  1297  (1913). 

37  PAAL  and  GERUM,  Berichte,  40,  2209  (1907)  and  41,  2273  (1908). 

88  FOKIN,  /.  Russian  Phys.  Chem.  Soc.,  40,  276  (1908). 

89  FOKIN,  Z.  Angew.  Chem.,  22,  1492  (1909). 

40  SKITA  and  MEYER,  Berichte,  45,  3579  (1912). 

41  PAAL  and  SCHWARZ,  Berichte,  48,  994  (1915). 

42  PAAL  and  SCHWARZ,  Berichte,  48,  1202  (1915). 

43  SKITA  and  MEYER,  Berichte,  45,  3589  (1912). 


560  CATALYSIS  IN  ORGANIC  CHEMISTRY  196 

a-Methyl-@-ethyl-propenal,  treated  in  acetic  acid  solution,  is  changed 
completely  into  a-methyl-pentanoL 

Mesityl  oxide,  in  water  solution,  goes  to  methyl-isobutyl-ketone,  but 
in  acetic  acid  solution,  into  methyl-isobutyl-carbinol.u 

560.  The  aromatic  nucleus  is  hydrogenated  more  or  less  readily. 
With  the  metal  prepared  by  the  germ  method,  benzene  is  transformed 
into  cyclohexane. 

Toluene,  in  acetic  acid  solution  under  2  atmospheres  pressure,  is 
changed  to  methyl-cyclohexane  and  benzoic  acid  into  hexahydrobenzoic.4* 

Cinnamic  aldehyde  is  transformed  into  phenylpropionic  aldehyde  in 
the  cold.  In  acetic  acid  solution  phenylpropyl  alcohol  is  obtained  mixed 
with  a  little  propyl-benzene,  while  with  a  larger  amount  of  the  catalyst 
and  a  pressure  of  3  atmospheres,  cyclohexyl-propyl  alcohol  is  obtained. 
Under  the  same  conditions,  in  acetic  acid  solution,  benzyl-aniline  fur- 
nishes hexahydrobenzyl-aniline  accompanied  by  cyclohexyl-amine  and 
methyl-cyclohexane. 46 

Phenylacetaldehyde  gives  the  corresponding  alcohol  with  a  little 
ethyl-benzene,  cyclohexanol,  cyclohexanone,  and  cyclohexane. 

Benzaldehyde  gives  toluene  and  methyl-cyclohexane  along  with  benzyl 
alcohol. 

Benzophenone  yields  dicyclohexyl-methane  at  60°. 

a  and  (3-Ionones,  in  acetic  acid  solution,  furnish  trimethyl-hy- 
droxybutylcyclohexane.*7 

Caryophyllene,  Ci5H24,  adds  H2  in  methyl  alcohol  solution.43 

561.  With  colloidal  platinum,  prepared  with  gum  arabic,  we  can 
obtain  piperidine  from  pyridine.^ 

The  addition  of  3H2  takes  place  with  various  homologs  of  pyridine, 
hydrogenated  in  acetic  acid  solution  under  atmospheric  pressure  or 
under  2  or  3  atmospheres.49 

The  pyridine-carbonic  acids  are  transformed  into  piperidinic  acids.50 
Quinoline  gives,  in  turn,  tetrahydro-  and  then  decahydroquinoline.415 
Diacetyl-morphine  adds  H2  and  cinchonine  yields  hexahydrocincho- 
nine.bl 

44  SKITA,  Berichte,  48,  1486  (1915). 

46  SKITA  and  MEYER,  Berichte,  45,  3589  (1912). 
4«  SKITA,  Berichte,  48,  1685  (1915). 

47  SKITA,  Berichte,  48,  1486  (1915). 

48  DEUSSEN,  Annalen,  388,  136  (1912). 

49  SKITA  and  BRUNNER,  Berichte,  49,  1597  (1916). 

60  HESS  and  LIEBBRANDT,  Berichte,  50,  385  (1917). 

61  SKITA  and  BRUNNER,  Berichte,  49,  1597  (1916). 


197  DIRECT  HYDROGENATIONS  OF  LIQUIDS  563 

II.    METHOD   OF  WILLSTATTER 

562.  The  process  consists  in  submitting  to  a  current  or  to  an  un- 
limited amount  of  an  atmosphere  of   hydrogen  gas,  the  substance 
dissolved  in  a  suitable  vehicle  and  intimately  mixed  by  means  of  con- 
stant agitation  with  the  platinum  or  palladium  black.    It  was  employed 
first  by  Fokin,  who  transformed  in  this  way  olelc  acid  dissolved  in  ether 
into  stearic  acid  by  a  current  of  hydrogen  in  the  cold  with  palladium 
or  platinum  black  as  catalyst.52 

But  Willstatter  is  the  one  who  has  generalized  this  method  by 
applying  it  to  various  uses. 

Platinum  black  prepared  according  to  the  method  of  Loew  (62) 
serves  best.53  Palladium  black  can  also  be  used:  it  is  prepared  by 
reducing  palladous  chloride  with  formaldehyde  in  the  presence  of  caus- 
tic soda.54  But  it  is  not  so  desirable  as  platinum  black. 

The  substance  dissolved  in  ether  or  in  any  other  inert  solvent  is 
treated  with  the  platinum  black  and  is  put  into  a  flask  which  is  continu- 
ally agitated  by  a  mechanical  shaking  machine  and  which  communicates 
with  a  gasometer  filled  with  hydrogen.  According  to  circumstances, 
quite  different  amounts  of  platinum  black  are  used,  varying  from  3 
to  33%  of  the  weight  of  the  substance. 

Dilution  of  the  material  is  not  indispensable  to  the  success  of  the 
method. 

Use  of  Platinum  Black 

563.  Willstatter  has  called  attention  to  this  quite  unexpected  fact, 
that  in  certain  cases  hydrogenation  by  means  of  platinum  black  is 
not  possible  unless  it  has  been  previously  charged  with  a  certain  pro- 
portion of  oxygen. 

In  most  cases,  platinum  black  containing  oxygen  or  free  from  oxy 
gen  may  be  used  indifferently,  as  in  the  hydrogenation  of  benzene  to 
cyclohexane;  on  the  contrary,  the  hydrogenation  of  pyrrol  requires 
platinum  black  absolutely  free  from  oxygen.  On  the  other  hand,  the 
decomposition  of  hydrazine  demands  that  the  platinum  black  that  is 
to  be  used  be  previously  aerated.55 

The  aeration  of  the  platinum  black  is  indispensable  for  the  hydro- 
genation in  acetic  acid  solution  of  phthalic  and  naphthalic  anhydrides 
and  the  reaction  does  not  continue  unless  the  apparatus  is  opened 

61  FOKIN,  J.  Russian  Phys.  Chem.  Soc.,  39,  607  (1907). 

63  Somewhat  improved  method  WILLSTATTER  and  WALDSCHMIDT-LEITZ,  Berichte 
54,  121  (1921).  — E.  E.  R. 

64  BRETEAU,  Div.  mtth.  d'hydr.  app.  au  Ph&nant,  Paris,  1911,  p.  25. 
86  PURGOTTI  and  ZANICHELLI,  Gaz.  Chim.  Ital,  34  (1),  57  (1904). 


664  CATALYSIS  IN  ORGANIC  CHEMISTRY  198 

from  time  to  time  for  the  aeration  of  the  black.  Oxygen  appears  to 
play  an  active  part  in  the  hydrogenation  which  is  indicated  by  the 
products  obtained.  For  phthalic  anhydride  the  products  are,  hexahy- 

/Ca\ 

drophthalid,  CeHnw  .O,   o.hexahydrotoluic  and  hexahydrophthalic 

acids,  and  for  naphthalic  acid,  tetrahydronaphthalid,  hexahydronaph- 
thalid,  decahydroacenaphthene,  Ci2H20,  and  tetrahydro-methyl(l)  naphtha- 
lene-carbonic acid  (8). 

The  influence  of  these  anhydrides  on  the  conditions  of  hydrogenation 
can  effect  even  the  hydrogenation  of  the  dibasic  acids  themselves; 
the  presence  of  the  anhydrides  prevents  this  from  taking  place  unless 
the  platinum  be  aerated.  Isophthalic  acid,  which  usually  contains  traces 
of  the  anhydride,  can  not  be  hydrogenated  except  with  aerated 
platinum.66  w 

564.  Nitro  Compounds.     The  reduction  of  nitro  or  nitroso  com- 
pounds to  amino  is  readily  effected  by  1  eg.  of  platinum  black  to  1  g. 
of  the  material  dissolved  in  ether  or  acetone.    A  few  minutes  are  suf- 
ficient  for    complete   reduction;     thus  p.nitrotoluene  is   changed  to 
p.toluidine,  l-nitrosonaphthol(@),  into  aminonaphthol.     But  the  nitroso- 
terpenes  are  changed  quantitatively  into  the  corresponding  hydrox- 
ylamines.68 

565.  Ethylene    Double    Bonds.      These    are    readily    saturated. 
Amylene  is  changed  to  pentane. 

&-Nitrostyrene,  dissolved  in  absolute  alcohol  or  in  glacial  acetic 
acid,  adds  a  single  atom  of  hydrogen,  two  molecules  combining 69 : 

CeHs .  CH  :  CH .  NO2  C6H5 .  CH .  CH2 .  NO2 

C6H5 .  CH  :  CH . N02  C6H5  .*CH .  CH2 .  N02 

Olelc  alcohol  is  readily  transformed  into  octadecyl  alcohol,  ethyl 
oleate  quantitatively  into  ethyl  stearate,  and  crude  alcohol  into  docosyl 
alcohol. 

66  WILLSTATTER  and  JACQUBT,  Berichte,  51,  767  (1918). 

67  In  a  more  recent  article  WILLSTATTER  and  WALDSCHMIDT-LEITZ  [Berichte, 
54,  113  (1920)  ]  show  that  the  presence  of  oxygen  in  the  platinum  black  is  neces- 
sary in  all  cases.    This  oxygen  is  gradually  used  up  by  the  hydrogen  during  the 
process  of  hydrogenation.    With  ethylene  compounds  the  addition  of  the  hydrogen 
is  so  extremely  rapid  that  the  desired  hydrogenation  may  be  accomplished  before 
the  catalyst  becomes  inactive  by  loss  of  its  oxygen  but  if  the  hydrogenation  is 
slow,  the  catalyst  may  require  revivification  by  aeration  at  intervals  during  the 
process.     In  this  respect  palladium  black  and  even  nickel  act  similarly  to  platinum 
black.  —  E.  E.  R. 

68  CUSMANO,  Lincei,  26  (2),  87  (1917). 

69  SONN  and  SCHNELLEMBERG,  Berichte,  50,  1913  (1917). 


199  DIRECT  HYDROGENATIONS  OF  LIQUIDS  567 


Phytene,  C20H4o,  gives  phytane,  C2oH42;  phytol,  C2oH39OH,  dihydro- 
phytol,  C2oH4iOH,  slowly  but  with  a  good  yield.  Geraniol  (416)  is 
hydrogenated  only  slowly  and  gives  the  corresponding  saturated  alco- 
hol at  the  end  of  several  days.60 

Linalool  furnishes  2,  6-dimethyl-octanol(6).61 

Safrol  and  isosafrol  are  hydrogenated  in  two  hours  to  dihydrosafrol. 
Likewise  eugenol  and  isoeugenol  pass  into  isopropyl-guaiacol.*2 

Piperonal-acetone  and  dipiperonal-acetone  are  transformed  into  the 
saturated  ketones.63 

Cholesterine,  in  ether  solution  with  one  third  its  weight  of  platinum 
black,  is  changed  into  dihydrocholesterine  in  two  days.64 

Oleic  acid  gives  stearic  and  ethyl  oleate  yields  ethyl  stearate.*5 

566.  Acetylene  Triple  Bonds.    The  acetylene  glycols  of  the  formula, 
RR':C(OH).C  •  C.C(OH)  :  RR',   give  the  corresponding  saturated 
glycols  and  also  certain  amounts  of  the  alcohols,  RR'  :C(OH)CH2.- 
CH2.CH2  :  RR'.64    Thus  2,  6-dimethyl-hexine(3)diol(2,  4)  furnishes  the 
saturated  glycol.66 

Dimethyl-diethyl-butine-diol,  which  adds  only  H2  with  colloidal  pal- 
ladium (548),  takes  up  2H2  with  platinum  black.67 

Dimethyl-diphenyl-butine-diol  can  add  H2  and  then  2H2  by  steps.68 

Octadi-ine-diol(l,8),  HOH2C.C  |  C.CH2.CH2.C  •  C.CH2OH,  hy- 
drogenated at  70°  in  alcohol^  solution,  gives  a  mixture  of  octane-diol 
(1,  8)  and  n.octyl  alcohol.69 

Octadwne-dioic  add,  H02C.C  •  C.CH2.CH2.C  !  C.C02H,  dissolved 
in  a  mixture  of  alcohol  and  ether,  furnishes  suberic  acid  in  four 
days.70 

567.  Aldehydes  and  Ketones.    Aldehyde  and  ketone  groups  can  be 
regularly  transformed  into  the  corresponding  alcohol  groups.    Crotonic 
aldehyde,  in  anhydrous  ether,  is  changed  in  eleven  hours  into  a  mixture 
of  70  %  butyric  aldehyde  and  30  %  butyl  alcohol.71 

80  WILLSTATTER  and  MAYER,  Berichte,  41,  1475  (1908). 

81  BARBIER  and  LOCQUIN,  Compt.  rend.,  158,  1555  (1914). 

82  FOURNIER,  Butt.  Soc.  Chim.  (4),  7,  23  (1910). 

63  VAVON  and  FAILLEBIN,  Compt.  rend.,  169,  65  (1919). 
84  WILLSTATTER  and  MAYER,  Berichte,  41,  2199  (1908). 

86  DUPONT,  Compt.  rend.,  156,  1623  (1913). 

88  ZALKIND,  J.  Russian  Phys.  Chem.  Soc.,  45,  1875  (1914),  C.  A.,  8,  1419. 

87  ZALKIND  and  Miss  MARKARYAN,  J.  Russian  Phys.  Chem.  Soc.,  48,  538  (1916), 
C.  A.,  11,  584. 

88  ZALKIND  and  KVAPISHEVSKH,  /.  Russian  Phys.  Chem.  Soc.,  47,  688  (1915), 
C.  A.,  9,  2511. 

89  LESPIEAU,  Compt.  rend.,  158,  1187  (1914). 

70  LESPIEAU  and  VAVON,  Compt.  rend.,  148,  1335  (1909). 

71  FOURNIER,  Bull.  Soc.  Chim.  (4),  7,  23  (1910). 


568  CATALYSIS  IN  ORGANIC  CHEMISTRY  200 

Acetone  is  changed  to  isopropyl  alcohol  in  water  solution  and  methyl- 
ethyl-ketone  is  changed  into  methyl-ethyl-carbinol  in  12  hours.  Diethyl 
and  dipropyl-ketones  are  similarly  reduced. 

The  transformation  into  the  alcohol  is  more  readily  effected  with 
cyclopentanone  dissolved  in  5  volumes  of  ether,  with  cyclohexanone  and 
with  the  meihyl-cyclohexanones. 

Mesityl  oxide  gives  first  methyl-isobutyl-ketone  and  then  methyl- 
isobutyl-carbinol. 

In  ether  solution,  phorone  yields  diisobutyl-ketone,  while  in  acetic 
acid  it  gives  diisobutyl-carbinol. 

Citral  in  ether  solution  gives  a  mixture  of  2,  6-dimethyl-octane  and 
2,  6-dimethyl-octanol  (S).72 

Menthone  yields  menthol  and  pulegone  gives  pulegomenthol.™  Carvone 
with  20  %  of  platinum  black  takes  up  in  succession,  H2,  2H2,  3H2  to 
form  carvotanacetone,  tetrahydrocarwne  and  finally  carvomenthol  slowly.74 

568.  Aromatic  aldehydes  are  transformed   almost  quantitatively 
into  alcohols,  which  is  a  valuable  reaction  since  other  methods  give 
hydrocarbons  (388).    With  10  g.  of  black  a  gram  molecule  can  be  hydro- 
genated  in  a  few  hours.     This  can  be  done  with  benzaldehyde,  methyl- 
salicylic,  benzoyl-salicylic,  and  anisic  aldehydes,  vanilline  and  its  methyl, 
ethyl,  acetyl,  and  benzoyl  derivatives,  piperonal,  which  gives  the  alcohol 
melting  at   54°,   and  cinnamic  aldehyde,  which  yields  phenyl-propyl 
alcohol.76 

At  70°  anisaldehyde  gives  anisalcohol  but  at  97°  it  is  polymerized. 
On  the  contrary,  acetophenone  takes  up  10  atoms  of  hydrogen  at 
once  to  form  ethyl-cyclohexane.76 

569.  Aromatic  Nucleus.      Aromatic    compounds    are   completely 
hydrogenated  to  cyclohexane  derivatives  on  the  condition  that  they  are 
perfectly  pure.    Traces  of  impurities,  particularly  sulphur  compounds, 
hinder  the  reaction.77 

Toluene  and  the  xylenes  are  hydrogenated  more  readily  than  ben- 
zene, and  higher  homologs  still  more  readily.  Butyl-benzene,  amyl- 
benzene,  hexyl-benzene,  octyl-benzene,  etc.,  up  to  pentadecyl-benzene  are 
readily  changed  in  acetic  acid  solution  into  the  corresponding  cyclo- 
hexane derivatives.78 

Durene  furnishes  hexahydrodurene. 

72  VAVON,  Ann.  Chim.  (9),  i,  144  (1914). 
78  VAVON,  Compi.  rend.,  155,  287  (1912). 
74  VAVON,  Compt.  rend.,  153,  68  (1911). 
76  Vavon,  Compt.  rend.,  154,  359  (1912). 

76  VAVON,  Compt.  rend.,  155,  287  (1912). 

77  WILLSTATTBE  and  HATT,  Berichte,  45,  1471  (1912). 

78  HALSE,  J.  prakt.  Chem.  (2),  92,  40  (1915). 


201  DIRECT  HYDROGENATIONS  OF  LIQUIDS  570 

Styrene  gives  ethyl-cyclohexane ; 79    and  phenol,  cyclohexanol.71 
Eugenol  adds  4H2  to  form  propyl-methoxy-cyclohexanol.*0 
Aniline  produces  chiefly  dicyclohexyl-amine  with  only  10  %  of  cyclo- 
hexyl-amine.    Chlortoluene  is  transformed  into  methyl-chlorcyclohexane.77 
In  ether  solution,  benzoic  acid  is  slowly  changed  to  hexahydrobenzoic 
acid  without  intermediate  products.81 

In  acetic  acid  solution,  p.aminobenzoic  acid  is  quantitatively  reduced 
to  p.aminocyclohexane-carbonic  acid  and  hydroxybenzoic  acid  is  similarly 
hydrogenated.82 

We  have  seen  above  (563)  that  phthalic  anhydride  can  be  hydro- 
genated by  means  of  platinum  black  aerated  from  time  to  time.  The 
ordinary  method  serves  well  for  phthalimide  which  gives  as  the  sole 
product,  hexahydrophthalimide : 83 

CH2.CH2.CH2.C(X 

;NH. 
CH2.CH2.CH2.CO/ 

570.  Terpenes.  Limonene,  in  ether  solution  with  25  %  of  its  weight 
of  platinum,  adds  H2  in  30  minutes  in  the  cold  to  form  carvomenthene, 
boiling  at  175°,  and  then  an  additional  H2  in  65  minutes  to  form 
menthane.^ 

Pinene,  500  g.  with  15  g.  platinum,  absorbs  hydrogen  rapidly,  60  1. 
per  hour  at  the  start,  and  at  the  end  of  24  hours  is  entirely  transformed 
into  dihydropinene,  boiling  at  166°  (477).  Camphene  gives  a  solid 
dihydrocamphene  melting  at  87°. 8B 

a-Thujene,  Ci0Hi6,  which  by  the  method  of  Sabatier  and  Senderens 
yields  menthane  (478),  is  totally  transformed  by  platinum  black  and 
hydrogen  under  25  to  50  atmospheres  in  two  days  into  thujane,  CioHig, 
boiling  at  157°,  the  inner  ring  remaining  intact.  Similar  transforma- 
tions take  place  with  /3-thujene  and  with  sabinene.*6 

Isoamyl-carvol  adds  2H2  to  give  the  corresponding  saturated 
alcohol.87 

The  sesquiterpenes,  Ci5H24,  as  well  as  their  ketone  and  alcohol 
derivatives,  add  4  or  6  atoms  of  hydrogen. 

79  WILLSTATTER  and  KING,  Berichte,  46,  527  (1913). 

80  MADINAVEITIA  and  BLANES,  Soc.  Espan.  Fis.  Quim.,  10,  381  (1913),  C.  A., 
7,  3500. 

81  WILLSTATTER  and  MAYER,  Berichte,  41,  1475  (1908). 

82  HOUBEN  and  PEAU,  Berichte,  49,  2294  (1916). 

83  WILLSTATTER  AND  JACQUET,  Berichte,  $i,  767  (1918). 

84  VAVON,  Bull.  Soc.  Chim.  (4),  15,  282  (1914). 

85  VAVON,  Compt.  rend.,  149,  997  (1909)  and  152,  1675  (1911). 

86  TCHOUGAEFF  and  FOMIN,  Compt.  rend.,  151,  1058  (1910). 

87  SEMMLER,  JONAS  and  OELSNER,  Berichte,  50,  1838  (1917). 


671  CATALYSIS  IN  ORGANIC  CHEMISTRY  202 

Thus  isozingiberene**  eudesmene*9  and  ferulene,*0  take  up  2H2.  The 
same  is  true  of  doremone,  d5H26O,  which  gives  tetrahydrodoremone  with- 
out alteration  of  the  ketone  group  and  of  doremol  which  forms  the  sat- 
urated alcohol.  Farnesol,  Ci5H26O  adds  3H2.90 

Betulol,  CisH^O,  adds  2H2  to  form  the  alcohol,  Ci5H280,  when  it 
is  hydrogenated  in  anhydrous  ether  solution.91 

571.  Complex  Rings.     Cyclo-octenone  is  changed  to  cyclo-octanone 
by  10%  of  its  weight  of  black.     Cyclo-octatriene  and  cyclo-odatetrene, 
CH:CH.CH:CH 

•     >  are  transformed  into  cyclo-octane.92 
CH:CH.CH:CH 

In  the  hydrogenation  of  the  latter,  the  first  three  H2  are  fixed  with 
about  the  same  velocity,  while  the  last  H2  is  added  only  about  half  so 
fast.93 

Naphthalene  adds  hydrogen  rapidly  to  form  the  dihydro-  and  then 
the  tetrahydro-  and  finally,  more  slowly,  decahydro-naphthalene** 

Phenanthrene,  dissolved  in  ether,  gives  dihydro-phenanthrene  (melt- 
ing at  94°),  in  two  days  in  the  cold,  or  in  8  hours  at  the  boiling  point 
of  the  ether.95  However,  Breteau  failed  to  obtain  any  hydrogenation 
in  cyclohexane  solution.96 

Santonine  yields  tetrahydro-santonine  when  hydrogenated  in  glacial 
acetic  acid.97  Sodium  santonate  takes  up  the  same  amount  of  hydrogen 
to  form  sodium  tetrahydrosantonate.98 

Pyrrol  adds  2H2  to  form  pyrrolidine." 

Indol,  in  glacial  acetic  acid,  yields  octahydro-indol,  an  alkaline 
liquid  with  a  disagreeable  odor  boiling  at  182°,  accompanied  by  a  little 
dihydro-indol.100 

572.  Quinine  sulphate  is  completely  hydrogenated  in  dilute  sul- 
phuric acid  solution  by  hydrogen  under  a  pressure  of  more  than  an 
atmosphere  to  dihydroquinine  sulphate,  the  hydrogenation  being  con- 

88  SEMMLER  and  BECKER,  Berichte,  46,  1814  (1913). 

89  SEMMLER  and  RISSE,  Berichte,  46,  2303  (1913). 

90  SEMMLER,  JONAS  and  ROENISCH,  Berichte,  50,  1823  (1917). 

91  SEMMLER,  JONAS  and  RICHTER,  Berichte,  51,  417  (1918). 

92  WILLSTATTER  and  WASER,  Berichte,  44,  3434  (1911). 

93  WILLSTATTER  and  HEIDELBERGER,  Berichte,  46,  517  (1913). 

94  WILLSTATTER  and  HATT,   Berichte,   45,    1471    (1912).  —  WILLSTATTER   and 
KING,  Ibid.,  46,  527  (1913). 

96  SCHMIDT  and  FISCHER,  Berichte,  41,  4225  (1908). 

96  BRETEAU,  Meth.  d'hydrog.  app.  au  Phenant,  Paris,  1911,  p.  20. 

97  ASAHINA,  Berichte,  46,  1775  (1913). 

98  CUSMANO,  Lincei,  22,  507  (1913). 

99  WILLSTATTER  and  HATT,  Berichte,  45,  1371  (1912). 

100  WILLSTATTER  and  JACQUET,  Berichte,  51,  767  (1918). 


203  DIRECT  HYDROGENATIONS  OF  LIQUIDS  575 

tinued  till  the  solution  does  not  decolorize  potassium  permanganate.101 
Dihydromorphine  and  dihydrocode'ine  can  be  obtained  in  the  same 

way.102 

Use  of  Palladium  Black 

573.  The  use  of  palladium  black  103  immersed  in  the  liquid  appears 
to  be  usually  less  advantageous  than  the  use  of  platinum  black.    How- 
ever, it  has  led  to  some  remarkable  results,  such  as  the  reduction  of 
carbonates  to  formates. 

574.  Reduction  without  Addition  of  Hydrogen.    The  most  important 
reaction  is  the  synthesis  of  formates  by  the  reduction  of  bicarbonates: 

KHC03  +  H2  =  HC02K  +  H20. 

This  requires  a  high  pressure  and  a  temperature  around  70°. 

In  a  silver  plated  bomb,  10  g.  potassium  bicarbonate,  200  cc.  water, 
and  1 . 5  g.  palladium  black  are  placed  with  hydrogen  at  60  atmospheres. 
After  heating  for  24  hours  to  70°,  74 . 7  %  of  the  salt  is  changed  to 
formate. 

The  reaction  takes  place  without  catalyst,  but  extremely  slowly, 
only  0.6  %  of  formate  being  produced  in  24  hours. 

The  potassium  bicarbonate  can  be  replaced  by  sodium  borate,  the 
bomb  then  being  filled  with  equal  volumes  of  carbon  dioxide  and  hy- 
drogen under  60  atmospheres.104 

The  reaction  can  be  carried  out  without  the  presence  of  the  alkali 
salt,  by  maintaining  a  mixture  of  carbon  dioxide  and  hydrogen  under 
high  pressure  in  the  presence  of  water  and  palladium  black.  By  working 
at  20°  and  under  a  pressure  of  110  atmospheres  a  1  %  solution  of  formic 
acid  is  obtained.105 

575.  Reduction  of  Acid  Chlorides.     Another  reaction  which  is 
peculiar  to  palladium  black  is  the  reduction  of  add  chlorides  to  aldehydes : 

R.COC1  +  H2  =  R.CHO  +  HC1. 

The  acid  chloride,  dissolved  in  a  hydrocarbon,  is  submitted  to  hy-< 
drogenation  in  the  presence  of  palladium  black  precipitated  on  barium 
sulphate. 

Benzoyl  chloride  gives  benzaldehyde  with  a  yield  of  97%;   butyryl 

101  VEREIN,  CHININPABR.  ZIMMER  &  Co.,  English  patent  3,948  of  1912. 

102  German  patent  260,233. 

103  Preparation  —  WILLSTATTER   and   WALDSCHMIDT-LEITZ,    Berichte,    54,    123 
(1921).  — E.  E.  R. 

104  BREDIG  and  CARTER,  Berichte,  47,  541  (1914). 

105  BREDIG  and  CARTER,  English  patent,  9,762  of  1915;   /.  S.  C.  /.,  34,  1207 
(1915). 


676  CATALYSIS  IN  ORGANIC  CHEMISTRY  204 

chloride  furnishes  50  %  of  the  aldehyde  and  stearyl  chloride  is  reduced 
to  its  aldehyde.105 

576.  Nitro  Compounds.     The  reduction  of  nitro  to  amino  com- 
pounds is  difficult  to  carry  out  with  palladium,  but  nitrobenzene  does 
give  aniline  on  prolonged  contact  with  an  excess  of  hydrogen  and 
palladium  black  in  alcohol  solution.107 

577.  Ethylene  and  Acetylene  Bonds.    Olelc  acid,  in  ether  solution,  is 
slowly  transformed  to  stearic  acid,  the  reduction  being  rapid  when  it 
is  carried  on  at  a  higher  temperature  and  with  hydrogen  under  pres- 
sure.   The  same  is  true  for  the  esters  of  ole'ic  acid  and  this  is  the  basis 
for  the  industrial  use  of  palladium  black  in  the  hardening  of  liquid 
fats  (946). 

/CH2 

Vinyl-trimethylene,  CH2:CH.CH(          ,  treated  in  the  cold  with 

XCH2 

hydrogen  under  35  atmospheres  in  the  presence  of  palladium  chloride, 
which  is  reduced,  yields  ethyl-trimethylene.108 

The  acetylene  glycols  of  the  type,  RR'  :  C(OH).C  \  C.C(OH) 
:  RR',  yield  mainly  the  saturated  hydrocarbons,  RR'  :  CH.CH2.CH2- 
CH  :  RR'.109 

Eugenol  stops  with  the  formation  of  dihydroeugenol,110  the  ring  not 
being  hydrogenated  as  with  platinum  black  (569). 

578.  Aromatic  Nucleus.    The  hydrogenation  of  the  aromatic  nu- 
cleus is  not  usually  effected  by  palladium  black,  but  the  hydrogenation 
of  hexahydroxybenzene  to  inosite  at  50-55°  may  be  mentioned.     The 
inosite  formed  melts  at  218°  as  does  natural  inosite.111 

579.  Phenanthrene  is  hydrogenated,  in  cyclohexane  solution,  by 
half  its  weight  of  the  black  to  tetrahydrophenanthrene.112 

Use  of  other  Metals  of  Platinum  Group 

580.  Ruthenium  Black.    The  black  prepared  by  formaldehyde  and 
ruthenium  chloride  solution  has  a  catalytic  activity  inferior  to  that  of 
platinum. 

If  0.05  g.  of  this  black  is  added  to  0.5  g.  cinnamic  acid  in  2  cc. 
glacial  acetic  acid,  phenyl-propionic  acid  is  formed  in  8  hours  without 

106  ROSENMUND,  Berichte,  51,  585  (1918). 

107  GERUM,  Inaug.  Dissertation,  Erlangen,  1908. 

108  FILIPPOV,  J.  Russian  Phys.  Chem.  Soc.,  44,  469  (1912). 

109  DUPONT,  Compt.  rend.,  156,  1623  (1913). 

110  MADINAVEITIA  and  BLANES,  Soc.  Espan.  Fis.  Quim.,  10,  381  (1913),  C.  A., 
7,  3500. 

111  WIELAND  and  WISHORT,  Berichte,  47,  2082  (1914). 

112  BRETEAU,  Div.  meth.  hydrog.,  Paris,  1911,  p.  26. 


205  DIRECT  HYDROGENATIONS  OF  LIQUIDS  583 

the  ring  being  attacked.     Toluene,  dissolved  in  acetic  acid  and  sub- 
jected to  hydrogenation  for  8  hours,  is  not  affected.113 

581.  Rhodium  Black.    Rhodium  black  is  more  active  than  ruthe- 
nium.   Under  the  conditions  given  above,  cinnamic  acid  is  transformed 
into  phenyl-propionic  in  3  hours  and  into  cyclohexyl-propionic  in  15 
hours.     Toluene  can  be  hydrogenated  to  hexahydrotoluene  in  12  hours 
by  10%  of  its  weight  of  the  black.113 

582.  Indium  Black.    This  black  prepared  by  reducing  the  chloride 
by  sodium  formate,  has  an  activity  entirely  analogous  to  that  of  ruthe- 
nium black  (580). 113 

583.  Osmium  Black.     This   black,  prepared  by  reducing  osmic 
anhydride  by  formic  acid,  does  not  effect  any  hydrogenation  of  cin- 
namic acid  in  5  hours.113 

Osmium  dioxide  has  been  mentioned  as  able  to  hydrogenate  oils 
when  used  to  the  amount  of  0.5  %,114  but  it  is  certain  that  it  acts  after 
it  is  reduced  to  the  metal  which  is  the  true  catalyst.118 

113  MADINAVEITIA,  Soc.  Espan.  Fis.  Quim.,  n,  328  (1913). 

"*  LEHMANN,  Arch.  Pharm.,  251,  152  (1913),  C.  A.,  8,  586  (1914). 

"*  NORMAN  and  SCHICK,  Arch.  Pharm.,  252,  208  (1914). 


CHAPTER  XII 
HYDROGENATIONS    (Continued) 

DIRECT   HYDROGENATION   OF    LIQUIDS   IN   CONTACT 
WITH  METAL    CATALYSTS    (Continued) 

III.  METHOD  OF  IPATIEF 

584.  THIS  method  consists  in  warming  the  substance  to  be  hy- 
drogenated  in  contact  with  nickel  or  nickel  oxide  and  hydrogen  com- 
pressed to  at  least  100  atmospheres  in  a  very  strong  container.    The 
hydrogenation  velocity  is  greater  when  the  oxide  is  used,  which  Ipatief 
attributes  to  the  real  catalytic  power  of  the  oxide.    As  we  have  seen 
above  (80),  catalytic  power  appears  to  belong  exclusively  to  the  metal; 
since  the  temperature  is  always  above  250°,  the  nickel  oxide  must  at 
least  in  part  be  reduced  to  the  metal  which  is  more  active  than  the 
metal  prepared  in  advance  and  which  has  been  subjected  to  incandes- 
cence more  or  less  intense  while  being  introduced  into  the  container, 
being  thereby  agglomerated  and  reduced  in  catalytic  power. 

The  nickel  is  frequently  replaced  by  copper,  copper  oxide,  iron  or 
palladium,  or  even  by  zinc  powder. 

585.  Apparatus.    The  apparatus  used  for  all  of  this  work  consists 
of  a  soft  steel  tube  lined  with  copper,  holding  250  to  275  cc.  and  capa- 
ble of  sustaining  600  atmospheres  at  600°. 1    It  is  heated  electrically  by 
a  nickel  resistance  wire.  Changes  of  pressure  are  shown  by  a  manom- 
eter.   If  the  apparatus  has  been  filled  with  hydrogen  at  a  certain 
pressure,  the  pressure  increases  according  to  the  rise  of  temperature, 
if  there  is  no  absorption  of  hydrogen  or  evolution  of  gas,  but  less 
rapidly  if  there  is  absorption  of  hydrogen,  while  if  there  is  decompo- 
sition with  evolution  of  gas,  the  pressure  increases  more  rapidly  and 
this  increase  measures  the  rate  of  decomposition. 

The  material  of  which  the  apparatus  is  constructed  appears  to 
influence  the  results  in  some  way.  Thus  in  a  bronze  tube  the  use  of 
reduced  copper  as  catalyst  did  not  effect  the  complete  hydrogenation 
of  the  aromatic  nucleus,  while  this  was  realized  in  an  iron  apparatus.2 

1  IPATIEF,  Berichte,  37,  2961   (1904).  —  J.  Russian  Phys.  Chem.  Soc.,  36,  786 
(1904),  C.,  1904  (2),  1020. 

*  IPATLBF,  J.  Russian  Phys.  Chem.  Soc.,  42,  1557  (1910). 

206 


207        LIQUIDS  IN  CONTACT  WITH  METAL  CATALYSTS       587 

Use  of  Nickel 

In  order  to  carry  out  a  hydrogenation,  about  25  g.  of  the  material 
to  be  hydrogenated  is  placed  in  the  apparatus  with  2  to  3  g.  nickel 
oxide  (NiO  or  Ni203)  and  hydrogen  is  admitted  to  100  atmospheres  at 
which  pressure  it  holds  about  one  gram  molecule  of  hydrogen.  The 
temperature  of  heating  may  reach  400°  -or  even  600°  and  the  resulting 
pressure  may  be  2.5  or  3  times  the  original,  i.e.  250  to  300  atmos- 
pheres. The  necessity  of  having  an  expensive  apparatus  and  the  real 
dangers  of  its  use  are  against  the  general  employment  of  the  method 
of  Ipatief ,  which  is  not  superior  to  the  method  of  Sabatier  and  Sender- 
ens  except  in  special  cases  where  the  slowness  of  hydrogenation  or  the 
need  of  high  pressures  requires  its  use.  Most  organic  substances  give 
the  same  products  by  both  methods. 

586.  Formation  of  Methane.    The  direct  hydrogenation  of  carbon 
in  the  presence  of  nickel,  oxide  of  nickel,  or  nickel  oxide  and  alumina, 
does  not  take  place  below  600°  under  moderate  pressures  of  hydrogen, 
but  under  very  high  pressures,  methane  is  produced  above  500°,  the 
amount  increasing  with  rise  of  temperature. 

The  reduction  of  carbon  dioxide  to  methane  which  takes  place  in- 
completely at  450°  under  ordinary  pressure,  is  not  more  complete  at 
high  pressures  even  with  an  excess  of  hydrogen.3 

587.  Ethylene  Double  Bonds.    The  hydrogenation  of  substances 
containing  ethylene  bonds  is  readily  effected. 

Olelc  acid  heated  a  long  time  at  100°  with  finely  divided  nickel 
and  hydrogen  at  25  atmospheres  is  not  affected,  but  under  60  atmos- 
pheres pressure  it  is  changed  to  stearic  acid  in  12  hours.  Liquid  fats 
are  transformed  to  solid.* 

50  g.  cottonseed  oil  with  3  g.  nickel  oxide  at  220-230°  with  hydrogen 
at  60  atmospheres  gave  in  4  hours  a  fat  with  iodine  number  (938)  of 
only  11,  while  at  ordinary  pressures  this  result  was  obtained  only  at 
255.05  6 

Dimethyl-allyl-carbinol  is  changed  to  dimethyl-propyl-carbinol  under 
the  same  conditions. 

At  140  to  150°,  mesityl  oxide  gives  methyl-isobutyl-ketone  mixed  with 
a  little  of  the  corresponding  alcohol. 

Cyclohexene  is  reduced  to  cyclohexane. 

8  IPATIEF,  J.  prakt.  Chem.  (2),  87,  479  (1913). 

4  FOKIN,  J.  Russian  Phys.  Chem.  Soc.,  38,  419  and  855  (1906). 

6  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  46,  302  (1914). 

6  With  high  speed  stirring  this  reduction  can  be  accomplished  in  about  the 
same  time  with  0.1  g.  nickel  on  infusorial  earth  with  hydrogen  at  atmospheric  pres- 
sure at  180°.  —  E.  E.  R. 


688  CATALYSIS  IN  ORGANIC  CHEMISTRY  208 

588.  Aldehydes  and  Ketones.     The  transformation  of  aliphatic 
aldehydes  and  ketones  into  the  alcohols  can  be  accomplished,  but  it  is 
limited  by  the  inverse  reaction  of  dehydrogenation  especially  when  the 
temperature  exceeds  200  to  250°. 

Isobutyric  and  isovaleric  aldehydes  are  partly  reduced  to  the  corre- 
sponding alcohols  at  250°  and  100  atmospheres. 

At  250°  acetone  is  completely  changed  to  isopropyl  alcohol  and  the 
same  is  true  of  various  aliphatic  ketones  at  around  200°.  At  about 
280°  the  hydrogenation  is  limited  by  the  inverse  reaction  which  in- 
creases with  elevation  of  temperature.  From  300  to  325°  acetone  no 
longer  gives  any  alcohol  since  isopropyl  alcohol  is  decomposed  into 
water,  propane  and  lower  saturated  hydrocarbons,  especially  methane.7 

Laevulose  in  solution  is  transformed,  at  130°  under  100  atmos- 
pheres, to  a-mannite,  glucose  into  sorbite,  and  galactose  into  dulcite. 

589.  Aromatic  Nucleus.     The  hydrogenation  of  the  aromatic  nu- 
cleus is  realized  in  all  cases. 

Benzene  is  totally  changed  to  cyclohexane  in  1.5  hours  at  250°  with 
8%  nickel  oxide.  Nickel  sesquioxide  gives  better  results  than  the 
monoxide.  At  300°  the  cyclohexane  produced  does  not  remain  but  is 
decomposed  into  benzene,  methane  and  carbon.8 

At  250°  diphenyl  is  reduced  to  dicyclohexyl  and  dibenzyl  to  dicyclo- 
hexylethane. 

At  245°  phenol  is  transformed  in  14  hours  to  cyclohexanol  accompan- 
ied by  some  cyclohexane.  At  200°  hydroquinone  gives  quinite.9  The 
product  is  a  mixture  of  the  cis  and  trans  forms,  but  the  yield  is  poor, 
as  most  of  the  diphenol  goes  into  resinous  products.10 

At  230°  under  100  atmospheres,  phenyl  oxide  gives  in  12  hours  a 
mixture  of  cyclohexyl  oxide,  cyclohexanol  and  cyclohexane.11 

Anisol,  C6H5OCH3,  in  24  hours  at  240°  under  100  atmospheres, 
gives  40%  hexahydroanisol  accompanied  by  cyclohexanol  and  cyclo- 
hexane. 

Guaiacol,  o.HO.C6H4.OCH3,  in  12  to  15  hours  at  220  to  240°  and 
100  atmospheres,  yields  hexahydroguaiacol  with  cyclohexanol  and  a 
little  cyclohexane.12 

7  IPATIBP,  J.  Russian  Phys.  Chem.  Soc.,  38,  75  (1906)  and  39,  681  (1907),  C.  A., 
i,  2877.  — Berichte,  40,  1270  (1907). 

8  IPATIEP,  J.  Russian  Phys.  Chem.  Soc.,  39,  681-693  (1907),  C.  A.,  i,  2877  and 
2878. 

9  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  38,  75  (1906)   C.,  1906,  (2),  86.— 
Berichte,  40,  1281  (1907). 

10  IPATIEP  and  LOUVOQOI,  J.  Russian  Phys.  Chem.  Soc.,  46,  470  (1914). 

11  IPATIEP  and  PHILIPOW,  J.  Russian  Phys.  Chem.  Soc.,  40,  501   (1908),  C., 
1908  (2),  1098.  —  IPATIEP,  Berichte,  41,  993  (1908). 

12  IPATIEP  and  LOUVOQOI,  J.  Russian  Phys.  Chem.  Soc.,  46,  470  (1914). 


209        LIQUIDS  IN  CONTACT  WITH  METAL  CATALYSTS       590 

590.  The  hydrogenation  of  phenols  having  unsaturated  side  chains 
is  accomplished  in  two  steps.  At  95°  and  30  to  50  atmospheres,  only 
the  side  chain  is  attacked  but  by  raising  the  temperature  to  185  to 
200°,  the  nucleus  is  also  hydrogenated. 

Thus,  anethol.  p . CH30 . C6H4 . CH  :CH.CH3,  with  10%  nickel  at 
95°  and  50  atmospheres  is  transformed  completely  in  4  hours  to 
methoxy-propyl-benzene,  but  20  hours  at  200°  produce  propyl-cyclo- 
hexane,  the  methoxy  group  being  reduced  to  water  and  methane. 

Likewise  eugenol,  H3C(HO)C6H3.CH2CH  :  CH2,  and  isoeugenol, 
HSC(HO)C6H3.CH  :CH.CH3,  furnish  methoxy-propyl-phenol  in  2  or 
3  hours  at  29°,  while  at  195°  in  7  hours,  the  chief  product  is  methoxy- 
propyl-cyclohexane,  H3CO  •  C6H10  •  C3H7,  the  phenol  group  being  elim- 
inated. 

The  methyl  ether  of  eugenol  adds  only  H2  at  95°,  but  in  10  hours  at 
210°,  the  same  product  is  obtained  as  from  eugenol. 

Safrol  and  isosafrol  are  not  hydrogenated  at  ordinary  pressure  at 
140  to  160°  with  constant  agitation  for  5  hours,  but  under  50  atmos- 
pheres at  93°,  dihydrosafrol,  boiling  at  228°,  is  obtained  in  2  hours. 
In  10  to  12  hours  at  180°,  a  product  is  obtained  boiling  at  207°  which 
appears  to  be  methoxy-propyl-cyclohexane.13 

By  50  hours  heating  at  220°  under  115  atmospheres,  aniline  gives 
40  to  50  %  of  cyclohexyl-amine,  about  10  %  dicyclohexyl-amine  and  some 
cyclohexyl-aniline. 14 

Diphenyl-amine  yields  dicyclohexyl-amine.15 

Benzaldehyde,  at  200°,  gives  toluene  and  methyl-cyclohexane,16  while 
at  280°  in  12  hours,  toluene,  dibenzyl  and  resinous  products  are 
obtained. 14 

Aromatic  ketones  act  as  they  do  in  Sabatier's  process  (389)  and 
yield  hydrocarbons,  benzophenone  going  into  diphenyl-methane  and 
benzo'ine  into  dibenzyl.16  17 

Ipatief  s  process  is  useful  for  the  hydrogenation  of  aromatic  acids, 
but  it  is  not  well  to  use  the  free  acids  which  attack  the  nickel 
nor  the  esters  which  give  poor  results  (ethyl  terephthalate  is  decom- 
posed into  ethyl  p.toluate,  methane  and  carbon  dioxide),  but  the 
alkaline  salts.  Thus  potassium  benzoate  gives  40  %  of  the  hexahydro- 
benzoate  at  280°  in  9  hours  and  sodium  benzoate  is  even  more  readily 
hydrogenated. 

»  IPATIEF,  Berichte,  46,  3589  (1913). 

14  IPATIEF,  Berichte,  41,  993-1001  (1908). 

15  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.  40,  491  (1908),  C.,  1908  (2),  1098. 
18  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  38,  75  (1906),  C.,  1906  (2),  86. 

17  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  38,  75  (1906)  and  39,  693  (1907), 
C.  A.,  i,  2877. 


691  CATALYSIS  IN  ORGANIC  CHEMISTRY  210 

Potassium  phthalate  gives  the  hexahydrophthalate  at  300°  in  good 
yield.18 

Sodium  cinnamate  gives  the  cydohexyl-propionate  at  300°  under  100 
atmospheres.19 

591.  Terpenes.     Terpene  compounds  undergo  the  regular  trans- 
formations.20 

Limonene  is  transformed  into  dihydrolimonene  and  then  into  men- 
thane  at  300-320°  under  120  atmospheres. 

At  265°  pinene  gives  pinane  and  menthane  at  300°. 

At  240°,  in  10  to  15  hours,  camphene  furnishes  an  isocamphane 
melting  at  57°  and  boiling  at  162.5°. 

At  280°,  under  120-130  atmospheres,  carwne  passes  into  carwmen- 
thone.  At  220°,  pulegone  gives  menthone,  which  at  280°  is  mixed  with 
menthane. 

Camphor  is  completely  changed  into  borneol  at  350°. 

592.  Various  Rings.    At  250°  under  120  atmospheres,  naphthalene 
gives,  in  turn,  tetrahydro-  and  decahydro-naphthalene. 

The  a-  and  /3-naphthols  are  changed  to  a-  and  j3-decahydronaphthols, 
melting  at  57°  and  99°  respectively.21 

Anthracene,  submitted  to  repeated  hydrogenations  at  260-270° 
under  100  to  125  atmospheres  for  10  to  16  hours,  gives  in  succession, 
tetrahydro-,  decahydro-  (m.73°)  and  finally  perhydroanthracene  (m.88°) 
and  at  the  same  time  is  partially  destroyed. 

At  400°,  phenanthrene  gives  better  results,  the  dihydro-  and  then 
the  tetrahydro-  being  obtained  and,  by  a  second  operation,  the  octa- 
hydro-  and  perhydrophenanthrene  with  the  odor  of  caoutchouc.22 

Quinoline  first  yields  tetrahydroquinoline  and  then,  almost  quantita- 
tively, decahydroquinoline.23 

Use  of  Iron 

593.  At  350-400°,  iron  transforms  aliphatic  aldehydes  and  ketones 
into  the  alcohols.     Acetone,  at  400°  and  103  atmospheres  in  20  hours 
yields  25  %  of  isopropyl  alcohol.    Isobutyric  aldehyde  gives  75  %  of  the 
corresponding  alcohol  at  350°,  but  acetaldehyde  is  partly  resinified  and 
partly  decomposed  into  carbon  monoxide  and  methane. 

18  IPATIEF  and  PHILIPOW,  J.  Russian  Phys.  Chem.  Soc.,  40,  501  (1908),  C.,  1908 
(2),  1098.  —  IPATIEF,  Berichte,  41,  993  (1908). 

19  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  41,  1414  (1909). 

20  IPATIEF,  Berichte,  43,  3546  (1910).  —  IPATIEF  and  MATOW,  Berichte,  45,  3205 
(1912). 

21  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  39,  693  (1907),  C.  A.,  i,  2877.  — 
Berichte,  40,  1281  (1907). 

22  IPATIEF,  JAKOWLEW  and  RAKITIN,  Berichte,  41,  996  (1908). 

28  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  40,  491  (1908),  C.,  1908  (2),  1098. 


211        LIQUIDS  IN  CONTACT  WITH  METAL  CATALYSTS       595 

The  hydrogenation  of  the  aromatic  nucleus  does  not  take  place, 
even  at  420°,  but  cyclohexane  is  brought  back  to  benzene.24  At  280° 
benzaldehyde  gives  a  mixture  of  toluene  and  dibenzyl.  The  same  result 
is  obtained  when  benzyl  alcohol  is  hydrogenated  at  350°  and  96  atmos- 
pheres.25 

Use  of  Copper 

594.  Copper,   or  copper  oxide  (certainly  reduced  to  the  metal), 
readily  permits  the  hydrogenation  of  ethylene  bonds  at  300  to  350° 
under  100  to  200  atmospheres,  but  when  used  alone  does  not  effect 
the  hydrogenation  of  the  benzene  ring.26 

Sodium  cinnamate  is  changed  to  the  phenyl-propionate*1 

Unsaturated  side  chains  of  phenols  are  saturated  at  270  to  300° 
without  modification  of  the  nucleus.28 

Acetone  yields  65%  of  isopropyl  alcohol  at  280-300°. 

Pinene  is  transformed  to  pinane,  while  camphene  gives  two  hy- 
drides, a  solid  melting  at  66°  and  a  liquid  boiling;  at  1620.29 

The  sodium  salts  of  the  two  naphthalic  acids  act  differently  when 
hydrogenated  with  copper  at  300°  under  100  atmospheres.  The  a  acid 
furnishes  tetrahydronaphthalene  directly,  while  the  /3  leads  first  to  the 
tetrahydro-naphthalic  acid  and  then  to  decahydronaphthalene.27 

Use  of  Other  Metals 

595.  Zinc  powder  can  cause  the  reduction  of  acetone  to  the  alcohol 
with  a  yield  of  50  %. 

By  using  palladium,  reduced  from  the  chloride  by  formates,  in  the 
proportion  of  1  g.  to  30  g.  of  the  substance  to  be  hydrogenated  under 
110  atmospheres  at  110°,  methyl-ethyl-acrole'ine,  C2H6.CH  :CH(.CH3)- 
•CHO,  is  transformed  in  2  or  3  days  to  methyl-pentanol. 

Mesityl  oxide  is  changed  in  2  days  at  110°  to  methyl-isobutyl-ketone. 

By  continuous  shaking  at  110°,  citral  is  reduced  to  the  decanol  with 
a  little  of  the  decane.  The  same  may  be  said  of  geraniol. 

Acetyl-acetone,  under  116  atmospheres  at  109°  is  changed  to  pen- 
tanediol  in  six  hours. 

Carbohydrates  dissolved  in  aqueous  alcohol  are  changed  to  the 

24  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  38,  75  (1906)  and  39,  681  (1907), 
C.  A.,  i,  2877. 

26  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  40,  489  (1908),  C.,  1908  (2),  1098. 

26  IPATIEF,  Berichte,  43,  3387  (1910). 

27  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  41,  1414  (1909). 

28  IPATIEF,  Berichte,  46,  3589  (1913). 

29  IPATIEF  and  DRACHUSSOF,  J.  Russian  Phys.  Chem.  Soc.,  42,  1563  (1911),  C., 
1911  (1),  1292. 


596  CATALYSIS  IN  ORGANIC  CHEMISTRY  212 

corresponding  hexites  at  110°  under  100  atmospheres.    Laevulose  yields 
mannite,  glucose  goes  into  sorbite  and  galactose  into  dulcite.™ 

IV.    HYDROGENATIONS  BY  NICKEL  IN  LIQUID 
SYSTEMS  UNDER  LOW  PRESSURES 

596.  Very  extensive  use  has  been  made  of  the  common  metals, 
particularly  nickel,  for  hydrogenation  in  liquid  medium  in  the  case  of 
liquid  fats  the  molecules  of  which  contain  ethylene  bonds.     The  de- 
scription of  the  methods  followed  and  the  results  obtained  is  the  special 
object  of  the  last  chapter  but  the  same  process  can  be  generalized  and 
extended  to  a  large  number  of  cases.     The  fundamental  condition  of 
success  is  a  sufficiently  energetic  agitation  in  the  hydrogen.  A  pressure 
of  several  atmospheres  is  useful  but  not  indispensable,  the  hydrogena- 
tion being  capable  of  being  carried  out  with  even  reduced  pressure. 
Simply  bubbling  the  hydrogen  through  the  liquid  is  not  sufficient. 

Brochet  has  tried  to  define  exactly  the  conditions  for  using  this 
method.31 

597.  Apparatus.      Different    forms    of    apparatus   may   be    used 
according  to  the  amount  of  the  work  to  be  done  and  the  magnitude  of 
the  pressure  to  be  used.    The  pressures  run  from  1  to  50  atmospheres, 
being  usually  around  10  to  15. 

A  red  copper  autoclave  of  1200  cc.  capacity,  which  can  operate 
satisfactorily  with  700  to  800  cc.  of  liquid,  may  be  used.  The  bronze 
cover  is  fitted  accurately  and  made  tight  with  lead  foil  packing,  being 
held  in  place  by  screw  clamps.  It  is  fitted  with  a  thermometer-well 
dipping  into  the  liquid,  a  pressure  gauge,  and  a  valve  for  the  intro- 
duction of  the  hydrogen.  The  apparatus  is  heated  electrically  by  a 
ferro-nickel  coil  insulated  by  asbestos  and  surrounded  by  sheet  asbestos 
to  keep  the  heat  in.  After  the  introduction  of  the  liquid  to  be  hydro- 
genated,  either  alone  or  in  solution,  and  the  addition  of  the  catalyst, 
the  autoclave  is  closed  and  connected  with  the  hydrogen  tank  which 
is  placed  along  side  on  the  platform  of  a  mechanical  shaker.  When 
the  operation  is  finished,  the  catalyst  is  filtered  off  and  may  frequently 
be  used  immediately  for  another  hydrogenation.32 

Brochet  uses  a  500  cc.  glass  cylinder  connected  with  a  hydrogen 
tank  by  means  of  a  bubble  counter  which  measures  the  amount  of  hy- 
drogen absorbed,  and  enables  one  to  follow  the  course  of  the  reaction. 

30  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  44,  1002,  and  1710  (1912);  C.  A.,  7, 
1171,  and  Berichte,  45,  3218  (1913). 

11  BROCHET,  Butt.  Soc.  Chim.  (4),  13,  197  (1913)  and  15,  554  (1914). 

82  A  convenient  laboratory  apparatus  with  high  speed  stirring  has  been  de- 
scribed by  REID,  J.  Amer.  Chem.  Soc.,  37,  2112  (1915).  —  E.  E.  R. 


213        LIQUIDS  IN  CONTACT  WITH  METAL  CATALYSTS         698 

598.  Catalysts.  The  nickel  used  is  prepared  by  reducing  at  about 
300°  the  oxide  prepared  by  calcining  the  carbonate,  nitrate  or  oxalate. 
After  cooling  in  a  current  of  hydrogen,  the  reduced  metal  is  plunged 
quickly  into  the  liquid  to  be  hydrogenated,  avoiding  contact  with  the 
air  as  much  as  possible. 

The  nickel  may  be  used  alone  as  a  metal  powder  or  incorporated 
with  inert  materials  such  as  infusorial  earth,  pumice,  or  charcoal  (126). 
This  incorporation  with  a  carrier  is  advantageous  and  gives,  on  re- 
duction at  450°,  a  catalyst  which  is  more  active  than  the  metal  alone 
reduced  at  350°,  and  a  fortiori  more  active  than  the  metal  alone 
reduced  at  4500.33 

Nickel  on  a  carrier  is  much  less  sensitive  to  toxic  agents  than 
nickel  alone.  Thus  for  the  metal  alone,  the  amount  of  hydrogen  sul- 
phide required  to  kill  the  catalyst  is  0.02-0.005  g.  to  0.5  g.  of  the 
catalyst,  according  to  the  method  of  preparation,  but  may  be  as  high 
as  0.1  g.  for  the  metal  on  a  porous  support.34 

We  have  seen  (584)  that  Ipatief  has  found  it  advantageous  with 
his  method  to  use  an  oxide  of  nickel,  such  as  NiO  or  Ni203,  in  place  of 
the  metal,  and  that  he  considers  the  oxide  more  active.  The  same 
substitution  has  been  proposed  for  the  hydrogenation  of  oils  (943),  in 
which  the  oxides  should  show  a  greater  activity  and  should  be  less 
susceptible  to  the  action  of  poisons,  particularly  sulphur.35  But  in  all 
cases  the  activity  of  the  oxide  may  be  explained  by  assuming  that  it 
is  partially  reduced  to  the  metallic  state,  the  metal  being  more  active 
on  account  of  being  formed  within  the  liquid  and  in  a  better  state  of 
subdivision.  This  is  the  opinion  of  Brochet,  who  considers  the  presence 
of  the  free  metal  necessary  for  hydrogenation  but  thinks  that  it  is 
activated  by  the  presence  of  foreign  substances,  such  as  its  oxide,  or 
salts  or  even  other  metals.36 

The  presence  of  metallic  nickel  in  the  oxide  which  is  used  as  cat- 
alyst has  been  denied  by  Erdmann,  who  bases  his  conclusion  on  the 
absence  of  conductivity  in  the  catalyst  after  it  has  been  freed  from 
fatty  material. 

At  any  rate,  it  is  well  established  that  at  the  temperature  at  which 
the  hydrogenation  of  oils  is  carried  on,  nickel  oxide  is  reduced  to  the 
suboxide,  NuO,  which  is  necessarily  slowly  reduced  at  these  same 
temperatures  to  the  free  metal,  the  presence  of  which  is  easily  shown 
by  the  direct  formation  of  nickel  carbonyl  by  the  action  of  carbon 

»  KELBER,  Berichte,  49,  55,  (1916). 

34  KELBER,  Berichte,  49,  1868  (1916). 

15  BEDFORD  and  ERDMANN,  /.  prakt.  Chem.  (2),  87,  425  (1913). 

*•  BROCKET,  Bull.  Soc.  Chim.  (4),  15,  770  (1914). 


699  CATALYSIS  IN  ORGANIC  CHEMISTRY  214 

monoxide  below  1000.37  Meigen  and  Bartels,38  Norman  and  Pungs,39 
and  later  Frerichs,  who  found  an  appreciable  conductivity  in  the  oxide 
which  had  served  for  the  hydrogenation  of  oil,40  have  come  to  the 
same  conclusion,  that  is,  that  the  oxide  is  inactive  in  hydrogenation, 
the  activity  belonging  only  to  the  free  metal. 

Erdmann  has  claimed  that  the  most  active  factor  in  hydrogenation 
is  a  suboxide,  such  as  Ni2O,  which  would  form  an  unstable  hydride 

/NiH 

with  hydrogen,  e.g.  CX  ,   which  is  capable  of  transferring  hydro- 

\NiH 

gen  to  the  molecules  which  can  take  it  up.  This  special  aptitude  of 
the  suboxide  has  been  claimed  by  Senderens  and  Aboulenc,  according 
to  whom  acetone  can  be  hydrogenated  at  110°  under  30  atmospheres 
pressure  by  the  suboxide  but  not  by  the  metal.41 

The  amount  of  catalyst  may  be  as  low  as  0.5  %  of  the  liquid  to  be 
hydrogenated,  but  it  is  better  to  use  larger  amounts  in  order  to  hasten 
the  reaction.42 

599.  Method  of  Work.    It  is  best  to  operate  at  least  20°  below  the 
boiling  point  of  the  liquid  used  as  solvent  so  that  its  vapor  will  not 
dilute  the  hydrogen  too  much.    If  substances  are  hydrogenated  with- 
out solvent,  100  to  150°  is  the  usual  range  of  temperatures  but  some- 
times from  150  to  200°. 

Alcohol,  more  or  less  diluted,  and  acetic  acid  are  the  most  favor- 
able solvents.  Benzene,  acetone,  ether,  and  ethyl  acetate  are  not  so 
good,  while  chloroform  is  rather  harmful.43 

The  course  of  the  reaction  is  easily  followed,  either  by  the  pres- 
sure gauge  or  by  the  bubble  counter,  which  shows  directly  the  volume 
absorbed.  This  enables  one  to  see  at  what  temperature  the  reaction 
goes  best. 

600.  Results  Obtained.     Nitro  derivatives  are  readily  changed  to 
the  corresponding  amines.     Azo  and  hydroazo  compounds  are  split 
into  two  amines;    but  by  operating  in  the  presence  of  caustic  soda 
which  moderates  the  action  of  the  catalyst,  it  is  possible  to  obtain 
azoxy,  azo,  hydrazo  and  finally  amino  from  aromatic  nitro  compounds.44 

87  SABATIER  and  ESPIL,  Compt.  rend.,  158,  674  (1914). 

38  MEIGEN  and  BARTELS,  J.  prakt.  Chem.  (2),  89,  296  (1914). 

39  NORMAN  and  PUNGS,  Chem.  Zeit.,  39,  29  (1915),  C.  A.,  9,  1552. 

40  FRERICHS,  Arch.  Pharm.,  253,  512  (1915). 

41  SENDERENS  and  ABOULENC,  Bull.  Soc.  Chim.  (4),  17,  14  (1915). 

42  In  hydrogenating  cotton  seed  oil,  0.1  %  nickel  on  a  carrier  is  ample  and  even 
0.01  %  gives  fair  results.  —  E.  E.  R. 

43  KELBER,  Berichte,  49,  55  (1916). 

44  BROCHET,  Bull.  Soc.  Chim.  (4),  15,  554  (1914). 


215        LIQUIDS  IN  CONTACT  WITH  METAL  CATALYSTS       601 

601.  Ethylene  Double  Bonds.  These  are  easily  saturated  at  low 
temperatures,  even  in  the  cold,  with  the  evolution  of  heat. 

A  mixture  of  ethylene,  with  hydrogen  in  excess,  is  changed  to  ethane 
by  being  passed  at  atmospheric  pressure  through  a  saturated  hydro- 
carbon in  which  a  nickel  catalyst  is  kept  in  suspension  by  rapid 
stirring.45 

a-Octene,  treated  in  alcohol  solution  with  20  %  of  active  nickel  and 
hydrogen  at  15  atmospheres,  is  completely  changed  to  octane  in  the 
cold.  This  can  be  accomplished  under  atmospheric  pressure  but  takes 
much  longer.46 

Ole'ic  acid  is  reduced  to  stearic  acid  at  250°  with  a  velocity  which 
is  nearly  proportional  to  the  pressure  of  the  hydrogen.47 

The  aliphatic  esters  of  ole'ic  acid  are  transformed  into  stearic  esters. 

The  salt  formed  by  combining  hot  oleic  acid  with  aniline  is  rapidly 
hydrogenated  to  a  brittle  solid  melting  at  76°. 48 

Cinnamic  acid,  in  twice  its  weight  of  amyl  alcohol,  is  completely 
changed  to  phenylpropionic  in  45  minutes  by  10%  of  nickel  at  100° 
under  15  atmospheres.  The  fact  that  the  acid  attacks  the  nickel  does 
not  hinder  the  reaction.  However,  it  is  better  to  use  sodium  cinnamate 
in  4  parts  of  water,  which  is  hydrogenated  in  the  cold. 

Methyl  cinnamate,  dissolved  in  methyl  alcohol,  is  changed  to  methyl 
phenylpropionate  49  in  the  cold  in  3  hours  under  15  atmospheres  pres- 
sure. Under  ordinary  pressure  the  action  is  much  slower,  the  reduc- 
tion of  ethyl  cinnamate  requiring  7  hours  at  70°. 50 

Anethol,  CH3O .  C6H4 .  CH  :  CH .  CH3,  is  rapidly  transformed  into 
methoxy-propyl-benzene  when  treated  without  solvent  with  10%  of 
nickel  at  60-80°  under  15  atmospheres,  but  requires  5  times  as  long 
at  1  atmosphere. 

Isosafrol,  dissolved  in  3  parts  of  alcohol  with  19  %  of  nickel,  adds 
H2  in  an  hour  at  65°. 

Geraniol  and  linalool  saturate  their  double  bonds,  but  allyl  alcohol 
does  not  at  70°  under  15  atmospheres,  neither  does  allyl  sulphocyanate. 
Piperonyl-acrilic  acid  gives  piperonyl-propionic  acid  in  the  cold  under 
15  atmospheres.51 

The  acetylene  triple  bond  is  also  saturated  without  difficulty. 

45  RATHER  and  REID,  J.  Amer.  Chem.  Soc.,  37,  2115  (1915). 

46  BROCHET  and  BAUER,  Bull.  Soc.  Chim.  (4),  17,  50  (1915),  and  Compt.  rend., 
159,  190  (1914). 

47  SHAW,  J.  Soc.  Chem.  Ind.,  33,  771  (1914). 

48  ELLIS  and  RABINOVITZ,  J.  Ind.  Eng.  Chem.,  8,  1105  (1916). 

49  BROCKET  and  BAUER,  Loc.  cit. 

60  BROCKET  and  CABARET,  Compt.  rend.,  159,  326  (1914). 

61  BROCHET  and  BAUER,  Butt.  Soc.  Chim.  (4),  17,  50  (1915). 


602  CATALYSIS  IN  ORGANIC  CHEMISTRY  216 

602.  Aldehydes   and    ketones.      Aldehydes    and    ketones    are    not 
appreciably   hydrogenated   under   atmospheric   pressure.      Thus   the 
allyl-ketones  dissolved  in  5  parts  of  alcohol  and  treated  at  60°  with 
hydrogen  under  atmospheric  pressure  are   hydrogenated  in   several 
hours  to  the  saturated  ketones  without  affecting  the  ketone  group.52 

On  the  contrary,  by  working  under  pressure  it  is  possible  to  change 
aldehydes  and  ketones  to  the  corresponding  alcohols.53 

603.  Various  Rings.    The  hydrogenation  of  the  benzene  ring  or  of 
similar  rings  is  much  more  difficult  to  attain  and  is  scarcely  realizable 
except  in  the  case  of  phenols  and  of  compounds  directly  related  to 
them.84 

With  ordinary  phenol  the  addition  of  hydrogen  takes  place  slowly 
from  50°  up  and  rapidly  between  100  and  150°  under  15  atmospheres, 
with  complete  transformation  into  cydohexanol  without  the  simul- 
taneous production  of  cyclohexanone. 

Likewise  several  hours  are  sufficient  for  the  hydrogenation  of  a- 
and  fi-naphthols  at  150°  under  15  atmospheres. 

Eugenol,  CH30(OH)C6H3.CH2.CH  :  CH2,  adds  H2  rapidly  at  60° 
and  15  atmospheres  to  form  propyl-methoxy-phenol  but  the  ring  is  not 
hydrogenated  unless  the  operation  is  carried  on  at  150°. 

Indigotine.  Indigo,  dry  or  in  paste,  suspended  in  water  containing 
a  little  caustic  soda  (10  g.  indigo  to  250  c.  dilute  caustic  soda)  is 
reduced  at  70°  by  5  g.  nickel  to  indigo  white  in  40  minutes.  The  same 
reaction  applies  to  thio-indigo  and  to  malachite  green  which  is  reduced 
to  the  leuco  base.66 

Hydrogenations  by  nascent  Hydrogen  in  Liquid  Systems  in 
contact  with  Metals 

604.  The  decomposition  of  formic  acid  by  the  catalytic  action  of 
metals  of  the  platinum  group  provides  hydrogen  (824)  which  can  be 
used  in  the  liquid  itself  to  effect  hydrogenations.     By  the  use  of 
spongy  or  colloidal  palladium,  cinnamic  acid  can  be  transformed  into 
phenylacetic  or  quinine  into  hydroquinine.™ 

62  COENUBERT,  Compt.  rend.,  159,  78  (1914). 

63  BROCHET  and  CABARET,  Compt.  rend.,  159,  326  (1914). 

84  The  hydrogenation  of  naphthalene  is  thoroughly  described  by  SHROETER, 
Annalen,  426,  1,  (1922).  — E.  E.  R. 

65  BROCKET,  Compt.  rend.,  160,  306  (1915). 

56  VEREIN.  CHININFABR.  ZIMMER  &  Co.,  German  patent,  267,306,  1914,  C.,  1914 
(1),  88. 


CHAPTER  XIII 

VARIOUS  ELIMINATIONS 

§  I.  — ELIMINATION  OF  HALOGENS 

605.  THE  classical  method  for  the  elimination  of  halogens  from 
chlorine,  bromine  or  iodine  compounds  is  treatment  with  sodium.1 
The  presence  of  benzene  or  petroleum  ether  retards  this  reaction  greatly, 
but  ordinary  ether  and  ethyl  acetate  usually  accelerate  it.2    The  use 
of  small  amounts  of  acetonitrile  greatly  facilitates  the  reaction.    Thus 
sodium  does  not  act  on  methyl  iodide  in  the  cold  but  the  addition  of 
one  or  two  drops  of  acetonitrile  causes  an  immediate  and  abundant 
evolution  of  ethane,  CHs.CH3. 

The  same  is  true  with  ethyl,  propyl,  isopropyl  and  allyl  iodides,  tri- 
methylene  bromide  and  benzyl  chloride.  Ethyl  cyanide  produces  a  similar 
catalytic  effect  and  propyl  cyanide  is  less  effective  while  benzonitrile 
and  benzyl  cyanide  have  no  such  effect.8 

§2.  — ELIMINATION  OF  NITROGEN 

606.  Diazo  Compounds.     In  many  important  reactions  of  aro- 
matic diazo  compounds,  a  molecule  of  nitrogen  is  eliminated.     Cu- 
prous salts  are  frequently  useful  or  indispensable  catalysts  for  these 
decompositions.    Copper  powder  can  produce  the  same  effects,  doubt- 
less through  the  initial  formation  of  cuprous  compounds. 

Diazobenzene  hydroxide,  C6H6 .  N  :  N .  OH  decomposes  immediately 
even  at  0°  in  the  presence  of  copper  powder  to  form  phenol  and  nitro- 
gen. The  copper  for  this  purpose  is  precipitated  by  zinc  dust  in  a 
saturated  solution  of  copper  sulphate,  washed  with  water  and  then 
with  a  very  dilute  solution  of  hydrochloric  acid  and  preserved  wet 
and  protected  from  the  air.4 

607.  Hydrochloric  acid  reacts  with  diazo  chlorides,  on  boiling,  to 
give  the  corresponding  aromatic  chloride,  on  condition  that  the  de- 

1  WURTZ,  Ann.  Chim.  Phys.  (3),  44,  275  (1855). 
8  ELBS,  Synth.  Darstel.  d.  KohlensL,  Leipzig,  1889,  2,  59. 
1  MICHAEL,  Amer.  Chem.  Jour.,  25,  419  (1901). 
4  GATTERMANN,  Berichte,  23,  1220  (1890). 

217 


608  CATALYSIS  IN  ORGANIC  CHEMISTRY  218 

composition  takes  place  in  the  presence  of  copper  powder  or  cuprous 
chloride*    We  have: 

C6H5.N2.C1  +  HC1  =  N2  +  C6H6.C1  +  HC1. 

The  cuprous  chloride  is  used  in  hydrochloric  acid  solution. 

This  action  of  cuprous  chloride  has  been  explained  by  assuming 
that  it  acts  in  the  presence  of  hydrochloric  acid  as  a  reducing  agent 
giving  cupric  chloride  and  hydrogen: 

2CuCl  +  2HC1  =  2CuCl2  +  2H 
and  2H  +  C6H5 .  N  :  NCI  =  C6H5 .  NH .  NHC1. 

The  hydrazine  compound  thus  formed  reduces  the  cupric  chloride : 
2CuCl2  +  C6H5.NH.NHC1  =  2CuCl  +  2HC1  +  C6H6.C1  +  N,. 

regenerated 

The  regenerated  cuprous  chloride  repeats  the  same  effects. 

608.  Hydrobromic   acid  reacts  in   a   similar   way  on   diazonium 
bromides  in  the  presence  of  cuprous  bromide.    The  cuprous  bromide  is 
prepared  by  warming  20  g.  copper  turnings  with  a  solution  of  12.5  g. 
copper  sulphate  and  36  g.  potassium  bromide  in  80  cc.  water  con- 
taining 11  g.  sulphuric  acid.6 

609.  Diazonium  salts  in  water  solution  with   sodium  nitrite,  in 
the  presence  of  copper  powder  or  moist  cuprous  oxide,  are  transformed 
into  nitro  compounds   (Sandmeyer  reaction) : 

C6H6.N2.C1  +  NaN02  =  C6H5.NO2  +  NaCl  +  N2. 

610.  Diazonium  salts  yield  the  corresponding  aromatic  isocyanates, 
C6H5.NCO,  when  treated  with  potassium  isocyanate  in  presence  of 
copper  powder.7 

611.  Hydrazine  Compounds.  Phenylhydrazine  is  decomposed  at  150° 
into  aniline,  nitrogen  and  ammonia,  on  contact  with  cuprous  chloride, 
bromide,  or  iodide: 

3C6H5.NH.NH2  =  3C6H6.NH2  +  N2  +  NH3. 

The  chloride  acts  more  rapidly  than  the  bromide  and  this  more 
rapidly  than  the  iodide.  When  more  than  1  %  of  the  chloride  is 
added,  the  decomposition  is  violent  and  almost  explosive.  The  crys- 
tallized compound,  CuI.2C6H6.NH.NH2,  which  may  serve  as  an 
intermediate  step  in  the  catalysis,  has  been  isolated.8 

6  SANDMEYER,  Berichte,  17,  1635  (1884). 

6  SANDMEYER,  Berichte,  17,  2652  (1884). 

7  GATTERMANN,  Berichte,  23,  1220  (1890). 

8  ARBUSOW  and  TICHWINSKY,  Berichte,  43,  2295  (1910)  and  J.  Russian  Phys. 
Chem.  Soc.t  45,  69  (1913),  C.  A.,  7,  2225. 


219  VARIOUS  ELIMINATIONS  614 

The  hydrazones  derived  from  hydrazine  and  saturated  cyclic  ke- 
tones  are  decomposed,  with  the  evolution  of  nitrogen,  on  contact  with 
a  small  fragment  of  solid  potash. 

Cyclohexone  hydrazone  gives   cyclohexane  in  a  violent   reaction: 

/CH2  .  CH2\  /CH2  .  CH2\ 

CH/  )C  :  N  .  NH2  =  CH/  )CH2  +  N2. 

\CH2  .  CH2/  \CH2  .  CH2/ 

In  every  case  the  hydrocarbon  obtained  contains  CH2  in  place  of 
the  CO  of  the  ketone.  Thus  hydrazones  from  the  methyl  cyclohexones 
yield  methyl  cyclohexane,  that  from  camphor  furnishes  camphane, 
CioHis  melting  at  158°,  and  that  from  fenchone  leads  to  fenchane, 
boiling  at  1510.9 

612.  3,  5.  —  Diphenyl-pyrazoline  heated  with  fragments  of  potash 
and  platinized  porous  porcelain  decomposes  into  nitrogen  and  diphenyl- 
cyclopropane.10 


/—  C  H2—  \  /CH2\ 

C6H5  .  CH(  )C  .  C6H5  -»  C6H6  .  CH^-  -  ^CH  .  C6H5  +  N,. 

\NH.1SK 


§  3.  —  SEPARATION  OF  FREE  CARBON 

613.  In  many  cases  the  dehydrogenation  of  hydrocarbons  leads  to 
the  separation  of  free  carbon  and  we  shall  see   (Chapter  XXI)  that 
various  finely  divided  metals  frequently  provoke  this  decomposition. 
But  it  is  well  to  consider  here  a  very  important  reaction  which  takes 
place  with  the  separation  of  carbon  from  carbon  monoxide  in  contact 
with  certain  substances. 

614.  Decarbonization  of  Carbon  Monoxide.    In  the  reduction  of 
the  oxides  of  iron,  nickel  and  cobalt  carried  on  above  400°  by  carbon 
monoxide,  it  has  long  been  known  that  carbon  is  deposited  and  this 
continues  at  the  expense  of  the  carbon  monoxide  according  to  the 
equation : 

2CO  =  C02  +  C. 

Mond  found  that  nickel  can  produce  this  effect  between  350  and 
450°. " 

Sabatier  and  Senderens  have  shown  that  the  reaction  takes  place 
with  reduced  nickel  above  230°,  elevation  of  temperature  accelerating 
the  decomposition  of  the  carbon  monoxide.  With  a  layer  of  nickel 

9  KIZHNER,  J.  Russian  Phys.  Chem.  Soc.,  43,  582  (1911),  C.  A.,  6,  347. 

10  KIZHNER,  J.  Russian  Phys.  Chem.  Soc.,  47,  1102  (1915),  C.  A.,  9,  3051. 

11  MOND,  LANGBB  and  QUINCKE,  Chem,  News,  62,  95  (1890). 


615  CATALYSIS  IN  ORGANIC  CHEMISTRY  220 

35  cm.  in  length  and  a  flow  of  gas  of  25  cc.  per  minute,  the  amounts 
of  carbon  dioxide  formed  from  100  cc.  of  the  monoxide  were: 

At  238°  1.2  cc. 

250°  3.8 

275°  17.9 

285°  23.2 

300°  40.5 

320°  49.0 

349°  and  above 50.0,  complete  transformation. 

The  reaction  may  be  complete  as  can  be  shown  by  experiment;  and 
besides,  the  inverse  formation  of  carbon  monoxide  from  carbon  and 
the  dioxide  does  not  begin  below  400°.  We  do  not  have  to  any  extent : 

C   +  C02  =  2CO, 
nor :  Ni  +  C02  =  NiO  +  CO. 

This  would  take  place  no  more  at  higher  temperatures,  such  as 
650°  and  800°. w 

615.  Reduced  cobalt  gives  rise  to  the  identical  reaction  at  above 
300°. 

Finely  divided  iron,  kept  at  445°  with  carbon  monoxide  for  several 
hours,  transforms  it  completely  into  carbon  dioxide  with  the  deposition 
of  carbon.13 

Finely  divided  platinum,  reduced  copper,  and  finely  divided  silver, 
do  not  produce  a  similar  effect  on  carbon  monoxide  below  450°. 

616.  The  separation  of  carbon  can  be  explained  by  assuming  the 
temporary  formation  of  nickel  or  cobalt  carbonyl  which  the  high  tem- 
perature decomposes  into  metal,  carbon,  and  carbon  dioxide.14 

But  we  can  explain  the  phenomenon  equally  well  by  the  mechan- 
ism which  is  apparent  in  the  case  of  iron.  At  low  temperatures,  iron 
tends  to  reduce  carbon  monoxide  to  carbon  with  the  formation  of 
ferrous  oxide: 

Fe  +  CO  =  FeO  +  C, 

but  at  a  higher  temperature,  there  is  the  formation  of  carbon  dioxide 
and  iron: 

FeO  +  CO  =  CO2  +  Fe. 

The  iron  thus  regenerated  can  repeat  the  first  reaction.  These  two 
successive  steps  may  take  place  likewise  with  nickel  and  cobalt  without 
our  being  able  to  perceive  the  intermediate  compound,  the  oxide,  since 

»  SABATIEB  and  SBNDERENS,  Butt.  Soc.  Chim.  (3),  29,  294  (1903). 
»  BOUDOUARD,  Ann.  Chim.  Phys.  (7),  24,  5  (1901). 
14  BERTHELOT,  Ann.  Chim.  Phys.  (6),  26,  560  (1892). 


221  VARIOUS  ELIMINATIONS  621 

the  reduction  of  the  oxide  by  the  carbon  monoxide  takes  place  at  a 
temperature  lower  than  that  at  which  the  metal  reduces  the  gas,  the 
oxide  of  the  metal  can  remain  only  in  inappreciable  amount.  From 
this  it  can  be  seen  that  the  reaction  will  take  place  better  with  nickel 
than  with  iron,  since  a  considerable  proportion  of  the  iron  is  actually 
transformed  into  the  oxide.15 

617.  Manganous  oxide,  which  dehydrogenates  alcohols  after  the 
manner  of  metals  (701),  appears  to  give,  doubtless  by  a  mechanism 
analogous  to  that  which  has  just  been  described,  a  certain  amount  of 
decomposition  of  carbon  monoxide  into  carbon  and  carbon  dioxide, 
but  it  is  always  small  below  350°. 16 

§4.  — ELIMINATION  OF  CARBON  MONOXIDE 

618.  The  decomposition  of  aldehydes  and  ketones  can  take  place 
as  a  consequence  of  the  elimination  of  carbon  monoxide  under  the  in- 
fluence of  catalysts,  either  finely  divided  metals  or  anhydrous  oxides 
acting  at  higher  temperatures. 

With  aldehydes  the  reaction  goes  more  readily  and  yields  chiefly: 

R.CO.H  =  CO+     RH. 

hydrocarbon 

619.  Reduced  nickel  acts  energetically  above  200°.     The  vapors 
of  propionic  aldehyde  are  rapidly  dissociated  at  235°  into  carbon  mon- 
oxide and  ethane.     Benzaldehyde  is  largely  decomposed  at  220°  into 
benzene  and  pure  carbon  monoxide.17 

Furfural  is  changed  by  nickel  at  270°  into  furfurane1* : 

CH  :  CH\  CH  :  CH\ 

>0         ->      •  )0. 

CH  :  (X--CHO  CH  :  CH/ 

620.  With  ketones  the  result  is  more  difficult  to  obtain.    Starting 
with  a  ketone  R.CO.R'  a  certain  amount  of  the  hydrocarbon  R.R' 
may  be  formed  but  the  d6bris  resulting  from  the  groups  R  and  R'  are 
the  chief  products. 

Acetone  is  decomposed  by  nickel,  slowly  at  240°  and  rapidly  at 
270°,  yielding  carbon  monoxide  and  the  CHa  radicals  which  give  a 
little  ethane  and  ethylene  but  chiefly  methane,  hydrogen  and  carbon.17 

621.  Reduced  copper  has  less  effect:   at  310°  its  action  on  propi- 
onic aldehyde  is  negligible  and  it  is  only  at  350°  or  better  at  400°  that 

"  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  485  (1905). 
M  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  315  (1910). 
17  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  474  (1905). 
"  PADOA  and  PONTI,  Lincei,  15  (2),  610  (1906),  C.,  1907  (1),  570. 


622  CATALYSIS  IN  ORGANIC  CHEMISTRY  222 

carbon  monoxide  and  a  mixture  of  ethane,  hydrogen  and  butane  is 
obtained.17  Its  action  is  energetic  on  formaldehyde  which  it  decom- 
poses almost  completely  into  carbon  monoxide  and  hydrogen.19  The 
resulting  carbon  monoxide  can  be  absorbed  by  caustic  soda  present  in 
the  mixture  and  furnish,  according  to  a  well  known  reaction,  sodium 
formate.20 

Copper  has  no  appreciable  effect  on  ketones  below  400°. 

622.  Platinum  sponge  and  particularly  platinum  black  have  an 
intense    destructive    action    on    aldehydes.      Propionic    aldehyde    is 
attacked  at  225°,  and  at  275°  decomposes  rapidly  into  the  same  gas- 
eous products  as  are  obtained  with  copper.21 

The  action  on  ketones  is  less  intense. 

623.  At  300°  palladium  black  decomposes  formaldehyde  completely 
into  carbon  monoxide  and  hydrogen  with  traces  of  carbon  dioxide  and 
methane.     Likewise  acetaldehyde,  propionic  aldehyde,  butyric  aldehyde, 
benzaldehyde,  and  the  toluic  aldehydes  are  more  or  less  split  at  temper- 
atures  around   300°  into   carbon   monoxide   and   the   corresponding 
hydrocarbons.22 

624.  The  decomposition  of  formic  acid  into  carbon  monoxide  and 
water  which  is  effected  by  certain  oxides,  titania,  blue  oxide  of  tungsten, 
alumina,  silica,  and  zirconia,  and  which  can  be  regarded  as  an  elimina- 
tion of  carbon  monoxide,  will  be  studied  later    (825),  as  also  the 
decomposition  of  formic  esters,  which  is  chiefly  according  to  this 
reaction    (866): 

H.CO2CnH2n+1  =  CO  +  CnH2n+i.OH. 

alcohol 

625.  Anhydrous  aluminum  chloride  can  decompose  acid  chlorides 
with  the  elimination  of  carbon  monoxide.     This  takes  place  with 
dichloracetyl  chloride  which  is  split  into  carbon  monoxide  and  chloro- 
form with  heptachlorpropane  as  a  by-product,  resulting  from  the  action 
of  the  chloroform  on  the  original  product.23 

§  6.  —  ELIMINATION  OF  HYDROGEN  SULPHIDE 

626.  Mercaptans.    Cadmium  sulphide  catalyzes  the  decomposition 
of  mercaptans  according  to  two  consecutive  reactions  exactly  analo- 
gous to  those  according  to  which  a  primary  alcohol  is  dehydrated  to  an 
ether  and  then  to  an  unsaturated  hydrocarbon  (701). 

19  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  345  (1910). 

20  LOEW,  Berichte,  20,  145  (1887). 

21  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  475  (1905). 

22  KUZNEZOV,  J.  Russian  Phys.  Chem.  Soc.,  45,  557  (1913). 
»  PRINS,  J.  prakt.  Chem.  (2),  89,  414  (1914). 


223  VARIOUS  ELIMINATIONS  628 

At  a  moderate  temperature,  we  have: 


sulphide 

At  a  higher  temperature,  a  more  rapid  decomposition  yields  hydro- 
gen sulphide  and  the  ethylene  hydrocarbon: 


Thus  ethyl  mercaptan,  C2H5.SH,  passed  over  cadmium  sulphide  at 
320°,  is  almost  completely  transformed  into  the  neutral  sulphide, 
(€2115)28,  while  at  380°  it  is  completely  decomposed  into  hydrogen 
sulphide  and  ethylene. 

Isoamyl  mercaptan  is  changed  into  isoamyl  sulphide  at  360°,  but 
above  400°  gives  hardly  anything  but  amylene. 

The  decomposition  of  primary  aliphatic  mercaptans  over  cadmium 
sulphide  at  regulated  temperatures  constitutes  a  regular  method  of 
preparing  primary  sulphides  from  the  mercaptans. 

627.  The  mechanism  of  the  decomposition  is  altogether  analogous 
to  that  of  alcohols  (169).    We  can  assume  the  formation  of  a  cadmium 
mercaptide  from  the  mercaptan  and  cadmium  sulphide.     This  would 
decompose,  according  to  the  temperature,  either  into  the  neutral  sul- 
phide or  into  the  ethylene  hydrocarbon  with  the  regeneration  of  the 
metal  sulphide  which  would  then  repeat  the  reaction,  thus  playing 
the  part  of  a  catalyst. 

We  have  at  first: 

CdS  +  2CnH2n+i.SH  =  (CnH2n+iS)2Cd  -f  H2S 

mercaptide 

then: 

(CnH2n-nS)2Cd  =  CdS  +  (CnH2n+1)2S 

sulphide 

and  at  a  higher  temperature: 

(CnH2n+1S)2Cd  =  CdS  +  H2S  +  2CnH2n. 

The  transitory  formation  of  the  cadmium  mercaptide  is  further 
indicated  by  the  change  of  color  of  the  sulphide,  which  takes  on  an 
orange  tint  quite  different  from  the  bright  yellow  of  the  original 
sulphide  and  retains  that  color  after  cooling  in  consequence  of  the 
persistence  of  a  certain  amount  of  the  mercaptide. 

628.  Secondary  mercaptans  have  a  stronger  tendency  to  decom- 
pose into  the  ethylene  hydrocarbons  but  can,  nevertheless,  furnish 
some  neutral  sulphide. 

Cyclohexyl  mercaptan,  passed  over  cadmium  sulphide  at  300°,  gives 


629  CATALYSIS  IN  ORGANIC  CHEMISTRY  224 

12  to  15%  of  the  sulphide  but  the  major  portion  is  decomposed  to 
cyclohexene,  while  at  350°  all  of  it  goes  into  cyclohexene.24 

629.  Thiophenols.    Aluminum  chloride  acts  on  a  warm  solution  of 
thiophenol   in   petroleum   ether,   eliminating   hydrogen   sulphide   and 
forming  the  diphenyl  sulphide.    At  the  same  time  some  thianthrene, 

/S\ 
C6EL        .CeH^  is  formed  by  loss  of  hydrogen.25 

630.  Formation  of  Thioureas.    The  thioureas  can  be  obtained  by 
the  reaction  of  primary  aromatic  amines  on  carbon  disulphide  in  the 
presence  of  a  little  sulphur  as  catalyst. 

Thus  1  part  each  of  aniline,  alcohol,  and  carbon  disulphide  and 
0.005  part  crystallized  sulphur  are  warmed  for  several  hours  on  the 
steam  bath  to  obtain  symmetrical  diphenyl-thiourea : 

/NH.C6H5 
CS2  +  2C6HBNH2  =  H2S  +  CS( 

\NH.C6H5 

The  ortho  and  para  toluidines,  the  naphthyl-amines  and  even 
p.aminophenol  give  the  same  reaction.26 

§6.  — ELIMINATION  OF  AMMONIA 

631.  Reduced  nickel  has  various  effects  on  primary,  secondary, 
and  tertiary  amines,  and  among  these  effects  one  is  the  elimination  of 
ammonia.27 

Above  300°  this  is  a  clean  cut  reaction  with  aliphatic  amines  con- 
taining less  than  5  carbon  atoms.  Thus  ethylamine  splits  up  into 
ammonia  and  ethylene,  which  at  that  temperature  is  in  turn  decom- 
posed into  carbon,  methane,  hydrogen  and  ethane  (910).  We  have: 

C2H5.NH2  =  NH3  +  C2H4. 

Amines  containing  five  or  more  carbon  atoms,  e.g.  amyl-amine, 
undergo  this  reaction  and  are  simultaneously  dehydrogenated  to 
nitriles.  This  is  true  for  benzyl-amine  also.28 

Aromatic  amines,  aniline  and  the  toluidines,  are  much  more  resist- 
ant, being  hardly  attacked  by  nickel  at  350°,  but  towards  500°  there 
is  elimination  of  ammonia  with  complete  destruction  of  the  molecule, 
according  to  a  complicated  reaction.29 

24  SABATIER  and  MAILHE,  Compt.  rend.,  150,  1570  (1910). 
26  DEUSS,  Rec.  Trav.  Chim.  Pays-Bos,  27,  145  (1908). 
26  HUQERSHOFF,  Berichte,  32,  2245  (1899). 
17  SABATIER  and  GAUDION,  Compt.  rend.,  165,  309  (1917). 

28  SABATIER  and  GAUDION,  Compt.  rend.,  165,  226  (1917). 

29  SABATIER  and  GAUDION,  Compt.  rend.,  165,  309  (1917). 


225  VARIOUS  ELIMINATIONS  633 

632.  By  heating  a-naphthylamine  for  8  hours  with  a  molecule  of 
aniline  in  presence  of  a  small  amount  of  iodine  (less  than  1  %),  am- 
monia  is   eliminated   and   phenyl-naphthylamine   is   formed   in   85% 
yield. 

The  use  of  very  small  proportions  of  iodine  enables  us  to  prepare 
the  secondary  amines  derived  from  a-naphthylamine  and  the  three 
toluidines,  ortho  and  para  anisidines,  and  meta  and  para  chloranilines, 
with  yields  superior  to  those  obtained  by  the  usual  methods. 

By  heating  fi-naphthylamine  on  the  steam  bath  for  4  hours  with 
less  than  1  %  of  iodine,  it  is  almost  quantitatively  changed  into  f$f$'- 
dinaphthyl-amine. 

Likewise  p.aminophenol  heated  below  200°  for  5  hours  with 
0.0025%  iodine,  loses  ammonia  and  yields  about  70%  pp' .  dihydroxy- 
diphenylamine.30 

633.  Cuprous  chloride  and  bromide  and  also  zinc  chloride  catalyze 
the  decomposition  of  the  phenylhydrazones  derived  from  the  lower 
aliphatic   aldehydes   and  ketones,   giving  ammonia  and  substituted 
indols. 

Thus  the  phenylhydrazone  of  methyl-ethyl-ketone  evolves  ammonia 
at  180°  when  0.2  %  of  cuprous  chloride  is  added  and  yields  2,  8-di- 
methyl-indol  in  2  hours. 

The  phenylhydrazone  of  propionic  aldehyde  gives  similarly  3-meth- 
yl-indol  (skatol).  With  copper  chloride  the  yield  is  60%  and  reaches 
73  %  with  zinc  chloride. 

With  aldehydes  there  is  some  formation  of  nitriles  resulting  from 
splitting  off  aniline  (635). 

The  formation  of  /3-methyl-indol  is  thus  represented: 


CH  HCX        NC C-CH3 

+NH3. 


S 


In  the  same  way,  the  phenylhydrazone  of  acetonyl-acetone  yields 
dimethyl-amino-phenyl-pyrrol.31 

With  the  phenylhydrazones  derived  from  higher  aliphatic  alde- 
hydes, this  reaction  is  of  little  importance  as  it  is  overshadowed  by  the 
formation  of  nitriles  (635). 

80  KNOEVENAQEL,  J.  prakt.  Chem.  (2),  89,  20  (1914). 

11  ARBUSOF  and  TIKHVINSKY,  J.  Russian  Phys.  Chem.  Soc.,  45,  73  (1913), 
C.  A.,  7,  2225.  —  ARBUSOF  and  FBIAUF,  Ibid.,  45,  694  (1913),  C.  A.,  7,  3599.— 
ARBUSOF  and  KHRUTZKII,  Ibid.,  45,  699  (1913),  C.  A.,  7,  3599. 


634  CATALYSIS  IN  ORGANIC  CHEMISTRY  226 

§  7.  —  ELIMINATION  OF  ANILINE 

634.  The  stability  of  aniline  in  the  presence  of  nickel,  which  has 
been  mentioned  above,  enables  us  to  predict  that  the  action  of  nickel 
on  alkyl  anilines  will  tend  to  split  off  aniline,  as  ammonia  is  elimi- 
nated from  the  alkyl  ammonias.    This  is  what  takes  place  with  methyl- 
aniline  at  250°.     Aniline  is  regenerated  with  the  separation  of  the 
group  CH2  which  decomposes  into  methane  and  carbon,  the  reaction 
being  nearly  thus: 

2C6H5.NH.CH3  =  2C6H5.NH2  +  C  +  CH4. 
With  ethyl-aniline,  we  have: 

C6H5 .  NH .  C2H5  =  C6H6 .  NH2  +  C2H4, 

the  ethylene  being  entirely  decomposed  by  the  nickel  (912)  into  carbon, 
methane,  ethane  and  hydrogen,  the  hydrogen  acting  on  the  aniline  to 
give  a  little  ammonia  and  benzene. 

Dimethyl-aniline  and  diethyl-aniline  behave  in  an  entirely  anal- 
ogous manner.32 

635.  The  phenylhydrazones  of  higher  aliphatic  aldehydes  are  de- 
composed by  copper,  zinc,  and  platinum  chlorides  into  nitrites  and 
aniline : 

R.CH  :N.NH.C6H5  =  R.CN  +  C6H5.NH2. 

This  is  true  for  isobutyric,  isovaleric,  and  isoheptylic  aldehydes.    The 
simultaneous  production  of  indols   (633)  is  of  little  importance.33 

82  SABATIER  and  GATJDION,  Compt.  rend.,  165,  309  (1917). 

83  ABBUSOF,  J.  Russian  Phys.  Chem.  Soc.,  45,  74  (1913). 


CHAPTER  XIV 
DEHYDROGENATION 

636.  WE  have  explained  direct  hydrogenation  by  means  of  finely 
divided  metals  by  the  formation  of  an  unstable  hydride,  produced 
rapidly  by  the  metal  and  capable  of  readily  giving  up  its  hydrogen. 
If   this   explanation   is   correct,   an   important   consequence   can   be 
readily  foreseen.    The  catalytic  metals,  nickel,  copper,  and  platinum, 
should  be  able  to  take  up  hydrogen  not  only  from  molecules  of  free 
hydrogen  but  also  from  other  substances  capable  of  furnishing  hydro- 
gen, and  consequently  to  be  dehydrogenation  catalysts,  a  prediction 
which  experiment  has  largely  verified. 

637.  This  capability  has  been  long  known  in  some   cases.      As 
early  as  1823  it  was  known  that  iron,  copper,  gold,  silver,  and  platinum 
had  the  power  of  greatly  facilitating  the  decomposition  of  ammonia, 
without  appreciable  alteration  of  the  metal.     The  decomposition  of 
the  ammonia  can  be  thus  effected  at  a  much  lower  temperature  than 
in  the  absence  of  these  metals.1 

In  1843,  Reiset  and  Millon  noticed  that  alcohol  vapor  passed 
through  a  tube  filled  with  fragments  of  porcelain  and  heated  to  300°, 
is  not  appreciably  decomposed,  but  that  decomposition  manifests 
itself  at  220°  in  presence  of  platinum  sponge.2 

In  1866,  Berthelot  noticed  that  the  presence  of  iron  favors  the 
decomposition  of  acetylene  at  a  red  heat,3  and  later  Schutzenberger 
stated  that  platinum  sponge  warmed  in  a  current  of  acetylene,  decom- 
poses it  with  incandescence,  giving  a  voluminous  mass  of  carbon  in 
which  the  metal  is  diffused.4 

This  active  decomposition  of  acetylene  was  rediscovered  in  1896 
by  Moissan  and  Moureu,  who  observed  it  also  with  recently  reduced 
iron,  cobalt,  and  nickel.5  A  similar  decomposition  of  ethylene  in  con- 
tact with  the  same  metals  at  300°,  was  obtained  in  1897  by  Sabatier 
and  Senderens,6  who  interpreted  it  by  assuming  the  temporary  for- 

1  DULONG  and  THENARD,  Ann.  Chim.  Phys.  (2),  23,  440  (1823). 

2  REISET  and  MILLON,  Ann.  Chim.  Phys.  (3),  8,  280  (1843). 

3  BERTHELOT,  Compt.  rend.,  62,  906  (1866). 

4  SCHUTZENBERGER,  TraiU  de  Chemie,  I,  724. 

5  MOISSAN  and  MOUREU,  Crnnpt.  rend.,  122,  1241  (1896). 

6  SABATIER  and  SENDERENS,  Compt.  rend.,  124,  616  (1897). 

227 


638  CATALYSIS  IN  ORGANIC  CHEMISTRY  228 

mation  of  a  metal  hydride  and  were  thus  led  to  apply  these  metals  to 
dehydrogenation  reactions  as  well  as  to  those  of  hydrogenation. 

638.  The  dehydrogenation  catalysts  are  primarily  the  metals,  and 
to  a  less  degree,  certain  anhydrous  metal  oxides  and  some  salts  derived 
from  these  oxides,  carbon  and,  in  exceptional  cases,  anhydrous  alu- 
minum chloride. 

The  effects  produced  by  these  catalysts  can  be  divided  into  several 
groups : 

1.  Dehydrogenation  of  hydrocarbons. 

2.  Return  of  hydroaromatic  compounds  to  aromatic  with  double 
bonds. 

3.  Conversion  of  primary  alcohols  to  aldehydes  and  of  secondary 
to  ketones. 

4.  Dehydrogenation  of  poly-alcohols. 

5.  Dehydrogenation  of  amines  to  nitriles. 

6.  Direct  synthesis  of  amines  from  hydrocarbons. 

7.  Formation  of  rings  by  loss  of  hydrogen. 

§  1.  —  DEHYDROGENATION  OF  HYDROCARBONS 

639.  Finely  divided  metals  exercise  an  important  dehydrogenating 
effect  on  hydrocarbons,  the  effect  being  greater  the  higher  the  tem- 
perature.    The  separation  of  hydrogen  is  always  accompanied  by  mo- 
lecular changes,  which  are  frequently  followed  by  condensation  into 
more  complex  hydrocarbons.     We  will  return  to  the  breaking  down 
and  building  up  of  hydrocarbons  by  catalysts  in  Chapter  XXI,  which 
is  devoted  to  that  subject,  and  will  content  ourselves  in  the  following 
paragraph  to  the  regular  passage  of  hydroaromatic  hydrocarbons  to 
the  aromatic  with  double  bonds. 

§2.  — DEHYDROGENATION  OF  HYDROAROMATIC 
COMPOUNDS 

640.  The  various   compounds  formed   by  the  hydrogenation  of 
stable  cyclic  compounds  tend  to  revert  to  the  latter  by  loss  of  hydrogen 
when  submitted  to  the  action  of  finely  divided  metals  at  tempera- 
tures higher  than  those  at  which  they  are  formed  directly.     Among 
the  metals,  reduced  nickel  shows  itself  as  particularly  active.7 

The  dehydrogenation  can  take  place  in  the  presence  of  excess  of 
hydrogen,  and  in  some  cases  the  excess  of  hydrogen,  far  from  hinder- 

7  This!  is  probably  a  reversible  reaction  reaching  a  definite  equilibrium  for  each 
temperature  and  pressure  of  hydrogen.  Quantitative  studies  are  most  desirable. 
—  E.  E.  R. 


229  DEHYDROGENATION  642 

ing  the  reaction,  regulates  it  by  favoring  the  maintenance  of  the  cyclic 
structure  and  diminishing  the  tendency  to  the  breaking  up  of  the 
molecule  into  many  fragments  (644). 

641.  Cyclohexane,  which  can  not  be  formed  by  the  direct  hydro- 
genation  of  benzene  by  the  aid  of  nickel  above  300°  (446),  suffers  a 
partial   dehydrogenation  to  benzene  above  300°,  but  a  part  of  the 
benzene  is  transformed  to  methane  by  the  liberated  hydrogen: 8 

3C6HU  =  2C6H6  +  6CH4. 

The  presence  of  a  current  of  hydrogen  stabilizes  the  molecule  to  a 
certain  extent  so  that  it  is  only  slightly  broken  up  at  350°.  At  400° 
about  30  %  of  the  cyclohexane  passing  over  the  nickel  with  the  hydro- 
gen is  decomposed  into  benzene.9 

With  methyl-cyclohexane  alone,  decomposition  begins  at  240°  and 
is  rapid  at  275°,  the  gas  evolved  then  containing: 

Methane 78  %  by  volume 

Hydrogen 22  %  by  volume 

The  condensed  liquid  contains  a  large  proportion  of  toluene. 

Ethyl-cyclohexane  is  attacked  slowly  at  280  to  300°  and  gives  a 
gas  containing  83%  methane  and  17%  hydrogen,  a  mixture  of  ethyl- 
benzene  and  toluene  being  condensed. 

The  1 ,  S-dimethyl-cyclohexane  acts  like  cyclohexane  and  is  stabilized 
by  an  excess  of  hydrogen.  At  400°,  the  dehydrogenation  to  m.xylene 
does  not  exceed  25  %.10 

Reduced  copper  exercises  a  similar  but  less  intense  action  which 
does  not  begin  till  above  300°. 

642.  Hydroxy  and  amino  substitution  products  of   cyclohexane 
hydrocarbons  undergo  dehydrogenation  still  more  readily  and  above 
350°  the  reaction  is  not  hindered  by  an  excess  of  hydrogen. 

In  the  presence  of  nickel  above  350°,  cyclohexanol  and  its  homologs 
come  back  to  the  phenol  condition.  This  effect  commences  at  even 
much  lower  temperatures:  when  cyclohexanone  is  hydrogenated  over 
nickel  at  230°,  25%  of  phenol  is  collected  along  with  the  cyclo- 
hexanol.11 In  a  current  of  hydrogen  at  360°  the  transformation  into 
phenol  is  practically  complete.12 

The  same  effect  is  even  more  important  for  the  cyclic  poly-alcohols 
and  also  for  the  amines  such  as  cyclohexyl-amine  which  tends  to  regen- 

8  SABATIER  and  MAILHE,  Compt.  rend.,  137,  240  (1903). 

9  SABATIER  and  DAUDIER,  Compt.  rend.,  168,  670  (1919). 

10  SABATIER  and  GAUDION,  Unpublished  results. 

11  SKITA  and  HITTER,  Berichte,  44,  668  (1911). 

»  PADOA  and  FABRIS,  Lincei,  17  (1),  111  and  125  (1908),  C.,  1908  (1),  1395  and 
1908  (2),  1103. 


643  CATALYSIS  IN  ORGANIC  CHEMISTRY  230 

erate  aniline  and  dicyclohexyl-amine  which  yields  diphenylamine  and 
cyclohexylaniline. 

The  hydrides  of  naphthalene  act  in  the  same  way:  the  higher 
hydrides  under  the  influence  of  nickel  at  200°  come  back  to  the 
tetrahydride,  and  this  regenerates  naphthalene  at  300°. 

Frequently,  as  in  the  case  of  cyclohexane,  the  liberated  hydrogen 
can  break  down  a  portion  of  the  hydrocarbon  into  larger  or  smaller 
aliphatic  fragments.  This  takes  place  with  dodecahydrophenanthrene, 
which  breaks  down  at  200°  into  lower  hydrides  and  various  aliphatic 
hydrocarbons,  while  the  hexahydride  is  regularly  dehydrogenated  to 
the  tetrahydride  at  220°,  which  in  turn  passes  to  phenanthrene  at  280°. 

With  nickel  at  300-330°,  the  perhydrides  of  anthracene  give  the 
tetrahydride  and  decomposition  products 

At  250°,  decahydrofluorene  returns  to  fluorene. 

643.  Unsaturated   cyclic   hydrocarbons,  cydohexenes,   cyclohexadi- 
enes,  as  well  as  the  terpenes  and  various  of  their  substitution  products, 
are  still  more  readily  dehydrogenated  by  nickel  even  in  a  current  of 
hydrogen. 

Cyclohexene  gives  benzene  almost  quantitatively  when  passed  over 
nickel  at  250°. 12  The  same  is  true  at  300°  in  a  current  of  hydrogen.13 

Cyclohexadiene,  CeH8,  passed  over  finely  divided  platinum  at  180°, 
yields  benzene,  but  this  is  mixed  with  cyclohexane,  which  is  stable  at 
this  temperature  and  which  results  from  the  utilization  of  the  liberated 
hydrogen.14 

644.  Limonene,  in  a  current  of  hydrogen  over  nickel  at  280-300°, 
is  changed  almost  entirely  into  cymene  accompanied  by  a  certain 
amount  of  cumene  and  simpler  aromatic  hydrocarbons. 

Menthene,  in  hydrogen  over  nickel  at  360°,  yield  80  %  of  cymene. 
Under  the  same  conditions,  pinene  and  camphene  are  dehydro- 
genated to  aromatic  hydrocarbons,  CioHu  and  lower.18 

/CH2.CH2V  /CH3 

645.  Eucalyptol,  or  cineol,  CH3 .  CT  >CH .  C(         ,  carried 


|\CH2.CH2/ 


along  by  a  current  of  hydrogen  over  nickel  at  360°  is  simultaneously 
reduced  and  dehydrogenated  to  form  cymene. 
Terpineol  undergoes  a  similar  reaction. 

/CH2.CO\  /CH3 

Pulegone,  CH3 .  CHf  XJ :  C'         ,  submitted  to  the  action 

\CH2.CH2/        \CH3 

13  SABATIER  and  GAUDION,  Compt.  rend.,  168,  670  (1919). 

14  BOESEKEN,  Rec.  Trav.  Chim.  Pays-Bos,  37,  255  (1918). 
16  SABATIEB  and  GAUDION,  Compt.  rend.,  168,  670  (1919). 


231  DEHYDROGENATION  649 

of  nickel  in  a  current  of  hydrogen  at  360°,  is  changed  into  a  mixture 
of  thymol  and  cresol,  formed  by  the  elimination  of  the  carbon  chain 
in  the  form  of  methane.15 

646.  Dodecahydrotriphenylene  is  completely  changed  to  triphen- 
ylene,  melting  at  198°,  by  passing  over  copper  at  450-500°. 16 

647.  Piperidine,  under  the  action  of  nickel  at  180  to  250°,  even  in 
the  presence  of  hydrogen,  is  totally  changed  to  pyridine:17 

/CH2 .  CH2\  /CH  :  CH\ 

CH/  )NH  ->  CH^-     ^N. 

\CH2 .  CH2/  \CH  :  CH/ 

Tetrahydroquinoline,  passed  over  nickel  at  180°,  gives  a  certain 
proportion  of  quinoline,  but  the  chief  product  is  skatol:18 

CH  CH2  CH 

HC      C      CH2      HC      C-    — C.CH3 
C      CH2      HC      C 


HC      C      CH2      HC      C      CH 

\   /  \   /          \   /  \   / 
CH     NH  CH     NH 


648.  If  dehydrogenation  is  carried  out  with  a  partially  hydrogen- 
ated  product,  the  hydrogen  set  free  by  the   action  of  the  metal  on 
one  portion  may  hydrogenate  the  other.    This  is  what  takes  place 
when  palladium  sponge  acts  on  methyl  tetrahydroterephthalate  which 
gives   1   part    methyl    terephthalate    and    2    parts   methyl    hexahydro- 
terephthalate.19 

649.  Palladium  black  is  an  active  dehydrogenation  catalyst  for 
the  hexamethylene  hydrocarbons.    The  action  begins  at  170°,  is  vigor- 
ous at  200°,  at  a  maximum  at  300°,  and  yields  only  hydrogen  and 
benzene  or  its  homologs.    At  100-110°,  the  inverse  action  takes  place, 
i.e.  there  is  hydrogenation  of  the  benzene,  but  this  does  not  take 
place    at    200°    even  in   excess   of   hydrogen.    Likewise   hexahydro- 
benzoic  acid  passes  to  benzoic.20    The  esters  of  hexahydrobenzoic  acid 
are    also    dehydrogenated,   but  methyl  cyclopentane-carbonate  is  not 
affected.21 

16  MANNICH,  Berichte,  40,  159  (1906). 

17  CIAMICIAN,  Lincei,  16,  808  (1907). 

18  PADOA  and  SCAGLIARINI,  Lincei,  17  (1),  728  (1908),  C.,  1908  (2),  614. 

19  ZELINSKY  and  GLINKA,  Berichte,  44,  2305  (1911). 

20  ZELINSKY  and  Miss  UKLONSKAJA,  Berichte,  45,  2677  (1912). 

21  ZELINSKY  and  Miss  UKLONSKAJA,  /.  Russian  Phys.  Chem.  Soc.  46,  56  (1913), 
C.  A.,  7,  2224. 


650  CATALYSIS  IN  ORGANIC  CHEMISTRY  232 

Below  300°,  cyclopentane  and  methyl-cyclopentane  22  and  cyclohep- 
tane  23  are  not  dehydrogenated. 

Platinum  black  acts  similarly  but  less  energetically.23 

§3.  —  DEHYDROGENATION  OF  ALCOHOLS 

650.  A  long  time  ago  Berthelot  noticed  that  the  vapors  of  ethyl 
alcohol  passed  through  a  progressively  heated  glass  tube,  begin  to 
decompose  at  around  500°,  that  is  at  nearly  a  dull  red  heat,  giving 
rise  to  two  simultaneous  reactions,  namely:  dehydration  with  sepa- 
ration of  ethylene  and  dehydrogenation  with  the  production  of  alde- 
hyde, the  reactions  being  further  complicated  by  the  decomposition  of 
the  ethylene  and  the  aldehyde  by  the  heat,  the  aldehyde  being  par- 
tially decomposed  into  carbon  monoxide  and  methane.24 

Various  primary  alcohols  undergo  analogous  decompositions  at  a 
dull  red  heat,  being  simultaneously  dehydrated  and  dehydrogenated. 
We  have: 

i  •  CH  :  CH2 


ethylene  hydrocarbon 

N  H2  +  CnH2n+1  .  CH2  .  CO  .  H 

aldehyde 

and  likewise: 

/,H20-f-(C6H5.CH)x 
C6H6.CH2Qir 

benzyl  alcohol      ^H2  +  C6H6.CO.H 

benzaldehyde 

Up  to  400°,  neither  of  these  reactions  takes  place  to  any  appre- 
ciable extent. 

Secondary  alcohols  react  more  readily  in  this  manner,  giving  hy- 
drocarbons by  dehydration  and  ketones  by  dehydrogenation,  the  one  or 
the  other  reaction  predominating  as  the  case  may  be.  Thus,  for 
secondary  aliphatic  alcohols,  ethylene  hydrocarbons  are  formed  rather 
than  ketones,  while  benzhydrol  yields  benzophenone  at  as  low  as  2900.25 

651.  In  the  presence  of  catalysts,  that  is  to  say  of  substances  capa- 
ble of  forming  temporary  chemical  combinations  with  one  of  the 
products  of  the  above  reactions,  the  corresponding  reaction  will  be 
realized  at  a  lower  temperature  and  rendered  more  or  less  rapid. 

22  ZELINSKY,  /.  Russian  Phys.  Chem.  Soc.,  43,  1220  (1911).  —  Berichte,  45,  3678 
(1912). 

,*  ZELINSKY  and  HERZENSTEIN,  J.  Russian  Phys.  Chem.  Soc.,  44,  275  (1912). 

24  BERTHELOT  and  JUNGFLEISCH,  Traitt  dim.  de  Chimie  Org.,  2nd.  Ed.  Paris, 
1886,  I,  256. 

26  KNOEVENAGEL  and  HECKEL,  Berichte,  36,  2816  (1903). 


233  DEHYDROGENATION  653 

Dehydrogenation  catalysts  should  specially  promote  the  decompo- 
sition of  alcohols  into  aldehydes  or  ketones,  while  dehydration  catalysts 
should  facilitate  the  formation  of  water  and  hydrocarbons. 

The  metals,  copper,  cobalt,  nickel,  iron,  platinum,  and  palladium, 
particularly  in  the  finely  divided  form,  are  dehydrogenation  catalysts,  and 
so  are  a  small  number  of  anhydrous  oxides,  e.g.  manganous,  though  to 
a  less  extent. 

On  the  contrary,  certain  metal  oxides  are  exclusively  dehydration  cata- 
lysts for  alcohols :  such  are  thoria,  alumina  and  the  blue  oxide  of  tungsten. 

Finally  a  large  number  of  substances,  oxides  and  salts,  have  both 
functions  and  can  to  very  variable  extents  cause  the  dehydration  and 
the  dehydrogenation  of  alcohols  at  the  same  time.  Beryllia  and  zir- 
conia  play  the  two  roles  almost  equally  well;  all  the  intermediates 
are  found  between  the  two  extremes  of  exclusive  catalysts.26 

652.  Of  all  the  dehydrogenation  catalysts,  the  one  that  serves  best 
for  the  regular  decomposition  of  primary  or  secondary  alcohols  into 
aldehydes  or  ketones,  is  reduced  copper,  which  in  practice  can  be 
replaced  by  the  very  finely  divided  copper  which  is  manufactured    fo 
imitation  gilding. 

Cobalt,  iron,  and  platinum  can  be  used,  but  with  poorer  results, 
while  nickel  is  the  least  suitable.27 

Use  of  Copper 

653.  Primary  Alcohols.     Primary  aliphatic  alcohols,  when  passed 
in  the  vapor  form  over  reduced  copper  kept  between  200  and  300°, 
are  regularly  decomposed  into  aldehydes  and  hydrogen,  the  conden- 
sate   containing,  along  with  the  aldehyde,  some  of  the  unchanged 
alcohol  and  a  little  of  the  corresponding  acetal.     The  practical  yield 
is  usually  above  50  %  with  less  than  5  %  of  higher  products  and  45  % 
of  the  alcohol  which  can  be  fractioned  out  and  put  through  again. 
This  is  a  very  advantageous  method  for  the  preparation  of  aliphatic 
aldehydes,  particularly  for  those  which,  on  account  of  low  volatility, 
are  difficult  to  prepare  by  oxidation  of  the  alcohols. 

The  transformation  can  never  be  complete,  even  when  a  long  train 
of  copper  is  used,  since  the  hydrogen  which  is  formed  can  be  added  to 
the  aldehyde  by  copper  above  200°.  Hence  the  reaction  is  limited  but 
the  conditions  are  favorable  to  the  decomposition  because  the  operation 
is  carried  on  in  the  presence  of  a  small  concentration  of  hydrogen. 

By  operating  under  reduced  pressure,  there  is  the  double  advan- 
tage of  a  more  ready  volatilization  of  the  alcohols  and  a  diminution 

26  SABATIER  and  MAILHE.  Ann.  Chim.  Phys.  (8),  20,  289  and  341  (1310). 

27  SABATIER  and  SENDERENS,  Compt.  rend.,  136,  738,  921  and  983  (1903). 


654  CATALYSIS  IN  ORGANIC  CHEMISTRY  234 

of  the  reverse  action  of  hydrogen,  and  consequently  increasing  the 
practical  yield. 

654.  The  apparatus  used  by  Sabatier  and  Senderens  is  the  same 
as  that  employed  for  hydrogenations  (347)  except  that  the  tube  for 
introducing  the  hydrogen  is  omitted.28 

Bouveault  has  used  a  vertical  tube  for  the  catalyst,  25-30  mm.  in 
diameter  and  of  varying  length,  up  to  1  m.  The  lower  extremity 
which  is  drawn  down  to  10  mm.  passes  through  the  stopper  of  a  flask 
in  which  the  alcohol  is  vaporized.  The  tube  is  filled  with  rolls  of 
copper  gauze  containing  copper  hydroxide,  resembling  cigarettes;  it 
is  heated  by  a  coil  of  resistance  wire  through  which  passes  a  current 
that  can  be  suitably  regulated.  The  reduction  of  the  copper  hydrox- 
ide is  effected  by  hydrogen  at  300°  and  should  be  carried  on  slowly  so 
as  to  leave  an  adherent  mass  of  copper. 

The  current  is  regulated  so  as  to  obtain  the  desired  temperature 
and  the  alcohol  vapors  pass  through  the  vertical  catalyst  tube  and 
from  it  into  a  fractionating  column  which  separates  the  more  volatile 
aldehyde  and  returns  the  less  volatile  alcohol  to  the  flask  to  be  reva- 
porized.  A  catalyst  tube  1  m.  long  is  sufficient  for  the  preparation 
of  500  g.  aldehyde  in  a  day.29  30 

It  is  evident  that  the  apparatus  may  be  connected  with  a  pump 
controlled  by  a  regulator  so  as  to  operate  in  a  partial  vacuum,  if  this 
is  desired. 

655.  If  the  temperature  is  above  a  certain  point,  the  aldehydes 
formed  are  partially  destroyed  by  contact  with  the  metal  with  elim- 
ination of  carbon  monoxide: 

R.CO.H  = 


But  except  in  the  case  of  formaldehyde  and  the  aromatic  alde- 
hydes, this  decomposition  is  not  yet  rapid  at  300°. 

This  decomposition  is  more  rapid  with  a  more  active  catalyst. 
With  methyl  alcohol,  using  a  light  violet  copper  prepared  by  the  slow 
reduction  of  the  precipitated  oxide,  there  is  a  rapid  evolution  of  gas 
which  contains  about  1  volume  of  carbon  monoxide  to  2  of  hydrogen  : 
the  formaldehyde  produced  has  been  completely  destroyed,  only  traces 
of  it  being  found  in  the  condensate.  We  have: 
H.CH2.OH  =  CO  +  2H2. 

On  the  contrary  with  compact  reddish  orange  copper,  prepared  by 
reducing  a  dense  oxide  at  a  dull  red,  the  evolution  of  gas  is  only  about 

28  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  332  (190$). 

29  BOUVEAULT,  Butt.  Soc.  Chim.  (4),  3,  50  and  119  (1908). 

80  This  apparatus  and  its  operation  are  more  fully  described  by  WEISMANN  and 
GABRAND,  J.  Chem.  Soc.,  117,  328  (1920).  —  E.  E.  R. 


235  DEHYDROGENATION  657 

one  twelfth  as  rapid,  but  it  is  practically  pure  hydrogen  and  almost 
all  of  the  formaldehyde  survives.31 

656.  Methyl  alcohol  is  decomposed  even  at  200°  and  very  rapidly 
at  280-300°. 

By  catalytic  decomposition  over  copper,  methyl  alcohol  can  be 
detected  in  ethyl  alcohol,  since  the  formaldehyde  produced  can  be 
characterized  by  the  violet  coloration  which  it  gives  with  morphine 
and  concentrated  sulphuric  acid.32 

The  destruction  of  the  formaldehyde  is  already  apparent  at  240- 
260°,  hydrogen  and  carbon  monoxide  being  produced  along  with  a 
little  methyl  formate  (225)  ,33  this  destruction  increasing  rapidly  with 
rise  of  temperature,  till  at  400°  at  least  75  %  is  decomposed. 

Ethyl  alcohol  is  decomposed  above  200°,  the  aldehyde  being  formed 
rapidly  at  250  to  350°,  without  complications.  At  420°,  16  %  of  the 
acetaldehyde  is  destroyed  and  the  gas  collected  contains  3  volumes 
of  methane  and  1  of  carbon  monoxide  to  6  of  hydrogen.34 

Propyl  alcohol  is  transformed  regularly  at  230  to  300°  and  at  420° 
one  fourth  of  the  aldehyde  is  destroyed. 

Butyl  alcohol  yields  the  aldehyde  well  at  220  to  280°,  and  at  370° 
only  one  sixth  is  destroyed. 

At  240  to  300°,  isobutyl  alcohol  is  easily  transformed  into  the 
aldehyde :  at  400°,  one  half  of  this  is  decomposed. 

Isoamyl  alcohol  yields  the  aldehyde  at  240  to  300°  without  compli- 
cations. At  370°  only  6  %  of  the  product  is  decomposed  and  at  430°, 
about  25  %.36 

An  aliphatic  Cio  alcohol  is  regularly  changed  into  the  aldehyde  by 
heating  in  Bouveault's  apparatus  under  reduced  pressure.36 

The  copper  is  never  fouled  by  carbonaceous  deposits  and  remains 
able  to  continue  the  reaction  indefinitely. 

657.  Benzyl  alcohol  is  transformed  less  readily  than  the  aliphatic : 
the  decomposition  does  not  begin  below  300°  but  is  satisfactory  there. 
At  380°  the  reaction  is  complex  and  some  toluene  and  benzene  are 
formed  along  with  the  benzaldehyde,  while  the  gases  evolved  contain 
carbon  monoxide  and  dioxide  along  with  the  hydrogen.     From  18 
parts  of  alcohol,  only  13  go  to  the  aldehyde,  the  other  5  forming 
benzene  and  toluene. 

Under  reduced  pressure,  phenylethyl  alcohol,  C6H5 .  CH2 .  CH2OH, 

31  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  344  (1910). 

32  MANNICH  and  GEILMANN,  Arch.  Pharm.,  254,  50  (1916),  C.  A.,  n,  1114. 

33  MANNICH  and  GEILMANN,  Berichte,  49,  585  (1916). 

34  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  463  (1905). 

35  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  463  (1905). 
3«  BOUVEAULT,  Butt.  Soc.  Chim.  (4),  3,  50  and  119  (1908). 


658  CATALYSIS  IN  ORGANIC  CHEMISTRY  236 

yields  phenyl-acetaldehyde  readily,  but  there  is  a  little  decomposition  of 
the  aldehyde  into  toluene  and  carbon  monoxide  and  there  is  also  some 
dehydration  of  the  alcohol  to  styrene,  CeHs.CH  :  CH2,  the  major  part 
of  which  is  hydrogenated  to  ethyl-benzene  or  condensed  to  the  slightly 
volatile  meta-styrene  which  remains  on  the  metal  and  weakens  its 
catalytic  activity. 

658.  The  unsaturated  allyl  alcohol,  CH2  :CH.CH2OH,  is  trans- 
formed over  copper  at  180  to  300°,  with  the  evolution  of  very  little 
hydrogen,  into  propionic  aldehyde,  with  a  slight  amount  of  acroleine. 
The  hydrogen  derived  from  the  decomposition  of  the  alcohol  serves 
to  hydrogenate  the  double  bond  of  the  aldehyde  formed    (432)  ,36 

It  is  the  same  way  with  undecenyl  alcohol,  CH2  :CH.(CH2)8.- 
CH2OH,  which  yields  only  the  saturated  aldehyde,  undecenal.  On 
the  contrary,  under  reduced  pressure,  geraniol  (416)  gives  citral 
almost  entirely.36 

659.  Secondary  Alcohols.    The  transformation  of  secondary  alco- 
hols into  ketones  with  the  separation  of  a  molecule  of  hydrogen  is  even 
more  readily  accomplished  by  finely  divided  copper  since,  the  ketones 
being  more  stable  than  the  aldehydes,  a  larger  temperature  interval 
is  available  in  which  to  effect  the  transformation.    Usually  even  at 
400°  there  is  no  appreciable  complication,  the  gas  evolved  is  pyre 
hydrogen.    The  immediate  yield  of  ketone  may  exceed  75%. 

As  in  the  case  of  the  aldehydes,  the  reaction  is  never  entirely  com- 
plete, since,  in  contact  with  copper  above  200°,  the  disengaged  hydro- 
gen is  capable  of  hydrogenating  the  ketone  to  regenerate  the  alcohol. 
But  the  hydrogenating  power  of  the  copper  is  much  less  than  its 
aptitude  to  decompose  the  alcohol  and  the  production  of  ketone  pre- 
dominates greatly.37 

Isopropyl  alcohol  is  decomposed  slowly  from  150°,  the  production 
of  acetone  being  rapid  at  250  to  430°,  without  separation  of  propylene. 

Secondary  butyl  alcohol  is  attacked  at  160°,  and  furnishes  butanone 
readily  at  300°  without  production  of  butylene. 

Secondary  octyl  alcohol  produces  only  the  octanone(2)  at  250  to 
300°.  It  is  only  above  400°  that  there  is  decomposition  into  carbon 
monoxide  and  hydrocarbons. 

660.  Over  copper  at  around  300°,  cyclohexanol  is  split  cleanly  into 
hydrogen  and  cyclohexanone.37 

At  300°,  o.methyl-cyclohexanol  is  transformed  into  o.methyl-cyclo- 
hexanone,  with  a  little  water  and  o.methyl-cydohexene  and  some 
o.cresol  which  are  readily  eliminated.  Results  almost  as  good  are 
obtained  with  the  meta  but  less  satisfactory  with  p.methyl-cyclohexanol. 

"  SABATHJR  and  SENDEBENS,  Ann.  Chim.  Phys.  (8),  4,  467  (1905). 


237  DEHYDROGENATION  664 

The  method  may  be  used  with  the  same  facility  with  the  various 
dimethyl-cyclohexanols  ,38 

661.  By  contact  with  copper  at  300°,  borneol  is  changed  very 
readily  and  almost  totally  into  camphor.39 

662.  Benzhydrol.    C6H5 .  CH  (OH) .  C6H5,    when    its    vapors     are 
passed  over  copper  at  350°,  yields  benzophenone,  which  is  largely 
changed  by  the  liberated  hydrogen  into  diphenyl-methane  and  partic- 
ularly into  symmetrical  tetraphenyl-ethane  (720). 

663.  The  method  is  suitable  for  transforming  a  secondary  alcohol 
group  into  a  ketone  group  even  in  mixed  compounds.    The  secondary 
alcohol-ketones  of  the  form  R.CH(OH).CO.R'  readily  furnish  the 
corresponding  a-diketones.40 

Under  the  same  conditions,  ($-hydroxy-esters  can  be  transformed 
into  ketone-esters.  Thus  ethyl  ft-hydroxy-isoheptoate,  (CH3)2CH.CH2.~ 
CH(OH).CH2C02C2H5,  is  changed  to  ethyl  J3-keto-isoheptoate.*1 

Use  of  Other  Metals 

664.  Nickel.    Reduced  nickel  acts  more  violently  on  the  alcohols 
than  does  copper  and  the  dehydrogenation  of  primary  or  secondary 
alcohols  is  always  accompanied  by  a  more  or  less  considerable  splitting 
up  of  the  aldehyde  or  ketone,  with  the  formation  of  carbon  monoxide 
which  may  be  more  or  less  profoundly  altered  by  the  nickel;   a  part 
being  hydrogenated  by  the  hydrogen  formed  from  the  alcohol  and  a 
part  being  changed  to  carbon  and  carbon  dioxide  (614).    The  sepa- 
ration of  the  carbon  monoxide  usually  begins  at  the  same  time  as  the 
decomposition  of  the  alcohol.42 

Methyl  alcohol  is  attacked  as  low  as  180°,  but  two  thirds  of  the  lib- 
erated formaldehyde  is  destroyed.  The  reaction  is  rapid  at  250°  but 
eight  ninths  of  the  aldehyde  is  destroyed  and  the  gas  evolved  contains 
only  45%  of  hydrogen  along  with  methane  and  carbon  monoxide. 
At  350°  there  is  no  longer  any  aldehyde  and  no  carbon  monoxide  :  the 
gas  is  a  mixture  of  methane  and  carbon  dioxide. 

Ethyl  alcohol  is  decomposed  from  150°  up,  rapidly  above  230°. 
As  low  as  180°,  almost  a  third  of  the  aldehyde  formed  is  decomposed, 
and  at  330°  its  destruction  is  complete. 

38  SABATIBR  and  MAILHE,  Ann.  Chim.  Phys.  (8),  10,  550,  554,  557  and  568 
(1907). 

"  GOLDSMITH,  English  patent,  17,573  of  1906;  /.  S.  C.  /.,  26,  777  (1907).— 
ALOY  and  BRUSTIER,  Bull  Soc.  Chim.  (4),  9,  733  (1911). 

40  BOUVEAULT  and  LOCQUIN,  Bull.  Soc.  Chim.  (3),  35,  650  (1906). 

41  BOUVEAULT,  Loc.  cit. 

42  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  469  (1905). 


665  CATALYSIS  IN  ORGANIC  CHEMISTRY  238 

The  results  are  similar  with  propyl  alcohol,  with  which  75  %  of  the 
aldehyde  is  decomposed  at  260°;  and  with  n.butyl  alcohol  with  which 
92%  of  the  aldehyde  is  decomposed;  and  for  isobutyl  alcohol.  With 
ordinary  isoamyl  alcohol,  the  destruction  of  the  aldehyde  already 
reaches  one  half  at  210°. 

Heptyl  alcohol,  submitted  to  the  action  of  nickel  at  220°,  gives 
only  a  small  amount  of  the  aldehyde,  the  chief  product  being  hexane 
resulting  from  its  decomposition  with  separation  of  carbon  monoxide.43 

665.  In  contact  with  nickel,  isopropyl  alcohol  is  slowly  decomposed 
into  acetone  and  hydrogen  from  150°  up.     The  reaction  is  rapid  at 
210°  but  about  12%  of  the  alcohol  that  is  transformed  is  split  into 
water,  ethane  and  methane. 

Secondary  butyl  alcohol  is  transformed  quite  regularly  above  200° 
but  20  %  of  the  product  is  already  decomposed,  while  at  310°,  80  %  is 
destroyed. 

For  methyl-hexyl-carbinol  the  decomposition  is  clean  at  250°  but  at 
that  temperature  already  the  methyl-hexyl-ketone  formed  is  mostly 
broken  down  into  carbon  monoxide,  methane  and  hexane,  only  a  third 
surviving. 

666.  Cobalt.    The  action  of  reduced  cobalt  on  primary  and  sec- 
ondary alcohols  is  between  that  of  nickel  and  that  of   copper.44 

667.  Iron.    The  action  of  iron  is  analogous  to  that  of  cobalt.    At 
high  temperatures,  600  to  700°,  it  causes  a  rapid  destruction.    An  iron 
tube  either  empty  or  filled  with  iron  turnings  decomposes  ethyl  alco- 
hol strongly  at  700°  giving  30  %  aldehyde  and  depositing  about  7  %  of 
carbon.46 

668.  Platinum.     Platinum  sponge  acts  on  alcohols  as  does  nickel 
but  its  action  does  not  begin  till  above  250°.    Besides  the  destruction 
of  the  aldehydes  is  inseparable  from  their  formation  and  always  pre- 
dominates. 

Around  250°  methyl  alcohol  is  split  cleanly  into  hydrogen  and  car- 
bon monoxide  with  no  methane  and  only  traces  of  formaldehyde. 

Ethyl  alcohol  is  attacked  at  270°,  and  at  370°  the  reaction  is  rapid, 
but  75%  of  the  aldehyde  is  decomposed  into  carbon  monoxide  and 
methane. 

Propyl  alcohol  is  split  above  280°,  but  at  310°  the  aldehyde  is 
almost  completely  decomposed  into  ethane  and  carbon  monoxide. 

The  results  are  better  with  secondary  alcohols  since  the  ketones 
are  more  stable  than  the  aldehydes. 

48  BOESEKEN  and  VAN  SENDEN,  Rec.  Trav.  Chim.  Pays-Bos,  32,  23  (1913). 
44  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  473  (1905). 
46  IPATIEF,  Berichte,  35,  1047  (1902). 


239  DEHYDROGENATION  673 

Isopropyl  alcohol  is  transformed  into  acetone  at  320°  without 
notable  complications  and  at  400°  the  destruction  of  the  acetone 
reaches  barely  3  %  of  the  product.46 

669.  Palladium.    The  considerable  affinity  that  this  metal  has  for 
hydrogen  seems  to  fit  it  for  the  dehydrogenation  of  alcohols.     Benz- 
hydrol  is  rapidly  decomposed  into  benzophenone   by  contact  with 
palladium  sponge.47 

670.  Zinc.    Around  650°  this  metal  decomposes  alcohols  strongly  : 
ethyl  alcohol  yields  60%  aldehyde  and  the  gases,  ethylene,  carbon 
monoxide  and  methane.     Isobutyl  alcohol  gives  75  %  of  aldehyde  and 
gas  which  is  largely  butylene. 

Brass,  an  alloy  of  copper  and  zinc,  acts  at  600°  like  zinc.48 


Use  of  Other  Materials 

671.  The  use  of  other  substances  to  dehydrogenate  alcohols  is  not 
advantageous  since  they  act  much  less  energetically  than  the  metals 
and  because  they  require  the  use  of  higher  temperatures  at  which  the 
aldehydes    are    decomposed    into    carbon    monoxide    and    saturated 
hydrocarbons. 

672.  Manganous  Oxide.    Its  action  hardly  begins  below  320°.    At 
360°  it  decomposes  methyl  alcohol  only  one  sixth  as  rapidly  as  compact 
red-orange  copper;  the  greater  part  of  the  formaldehyde  survives  and 
the  hydrogen  is  nearly  pure. 

At  360°  the  decomposition  of  ethyl  alcohol  is  only  one  fortieth  as 
rapid  as  with  light  copper  and  a  part  of  the  aldehyde  is  already  de- 
composed into  ethane,  carbon  monoxide  and  even  carbon  dioxide,  the 
latter  being  formed  from  the  carbon  monoxide  with  a  corresponding 
deposit  of  carbon,  the  reaction  being  similar  to  that  produced  by 
metals  (614). 

Propyl,  isoamyl  and  benzyl  alcohols  give  analogous  results.49 

673.  Stannous  Oxide.    This  acts  above  300°  as  a  dehydrogenation 
catalyst  after  the  manner  of  the  metals,  but  is  slowly  reduced  mean- 
while into  metallic  tin,  which  is  easy  to  see  in  the  oxide.    This  finely 
divided  tin  seems  to  possess  a  catalytic  power  similar  to  that  of  the 
oxide  so  that  the  mixture  of  metal  and  oxide  continues  to  split  alco- 
hols into  aldehydes  and  hydrogen  for  a  long  time,  but  as  the  reaction 
temperature  is  above  220°,  the  melting  point  of  tin,  the  tiny  globules 

46  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  473  (1905). 

47  KNOEVENAGEL  and  HECKEL,  Berichte,  36,  2816  (1903). 

48  IPATIEF,  Berichte,  34,  3579  (1901)  and  37,  2961  and  2986  (1904). 

49  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  313  (1910). 


674  CATALYSIS  IN  ORGANIC  CHEMISTRY  240 

of  metal  resulting  from  the  reduction  of  the  oxide  gradually  coalesce 
into  larger,  and  consequently  the  activity  diminishes. 

Thus  with  ethyl  alcohol,  the  brownish  orange  stannous  oxide  (re- 
sulting from  the  reduction  of  stannic  oxide  by  the  alcohol  vapors) 
commences  to  act  at  260°.  At  350°  the  velocity  of  the  reaction  is 
almost  half  as  great  as  with  the  same  volume  of  very  light  reduced 
copper.  The  disengaged  hydrogen  is  almost  pure,  the  acetaldehyde 
being  only  slightly  decomposed.  At  the  end  of  four  hours  the  velocity 
of  the  reaction  is  reduced  by  half. 

Amyl  alcohol  yields  the  aldehyde  regularly  at  340°. 

Methyl  alcohol  is  attacked  above  260°  with  the  production  of  form- 
aldehyde. At  350°  the  most  of  this  is  decomposed  into  carbon  mon- 
oxide and  hydrogen.60 

674.  Cadmium  Oxide.    This  behaves  like  stannous  oxide  and  de- 
hydrogenates  while  it  is  reduced  at  the  same  time  to  the  metal  which 
possesses  a  catalytic  activity  differing  little  from  that  of  the  oxide. 
Thus  with  ethyl  alcohol  at  300°  the  reaction  is  about  one  tenth  as 
rapid  as  with  the  same  volume  of  very  active  copper  and  maintains 
itself  for  a  long  time  in  spite  of  the  progressive  reduction  of  the  oxide. 

Benzyl  alcohol  acts  in  exactly  the  same  way :  at  350°  there  is  a 
slow  reduction  of  the  oxide  and  at  the  same  time  a  splitting  of  the 
alcohol  into  benzaldehyde  and  hydrogen.  At  380°  the  benzaldehyde  is 
partially  decomposed  into  benzene  and  carbon  monoxide.  The  entire 
absence  of  the  resinous  hydrocarbon  (714)  indicates  that  there  is  no 
dehydration. 

With  methyl  alcohol,  the  splitting  which  begins  at  250°  is  quite 
rapid  above  300°  and  produces  formaldehyde  which  is  partially  de- 
composed into  carbon  monoxide  and  hydrogen.81 

675.  Other  Oxides.    Most  non-reducible  metallic  oxides  are  mixed 
catalysts  for  alcohol,  causing   dehydration   and   dehydrogenation  at 
the  same  time.    For  some  :  uranous  oxide,  blue  oxide  of  molybdenum, 
vanadous  oxide,  V203,  zinc  oxide,  dehydrogenation  predominates. 

In  another  group :  beryllium  oxide,  zirconium  oxide,  chromic 
oxide,  Cr2O3  (calcined  above  500°),  the  dehydrogenating  and  dehy- 
drating powers  are  about  equal. 

For  a'third  group  :  chromic  oxide,  Cr2O3  (not  calcined),  titanium 
oxide,  silicon  dioxide,  dehydration  predominates. 

676.  With  reference  to  methyl  alcohol  the   classification   of  the 
oxides  is  quite  different  since  in  this  case  dehydration  can  not  take 
place  except  by  the  formation  of  methyl  ether  and  the  conditions  are 

60  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  309  (1910). 
"  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  302  (1910). 


241  DEHYDROGENATION  678 

not  comparable.  Except  alumina,  which  at  390°  only  dehydrates, 
and  several  oxides  (thoria,  blue  oxide  of  tungsten,  chromic  oxide  and 
alumina  above  350°)  which  are  mixed  catalysts,  all  metallic  oxides 
dehydrogenate  methyl  alcohol  with  the  production  of  formaldehyde 
which  is  more  or  less  decomposed  into  carbon  monoxide  and  methane. 
The  following  table  indicates  the  volume  of  gas  obtained  per  min- 
ute with  the  same  volume  of  various  catalysts  employed  under  the 
same  conditions. 

Oxides  Volume  of  gas  in  cc.  per  minute. 

Formaldehyde  remaining  almost  entirely;   the  gas  is  nearly  pure  hydrogen. 

BeO very  small 

SiO2 0.3 

Ti02 1.2 

ZnO 1.5 

Zr02 1.8 

MnO 2.0 

A12O8 6.0 

Formaldehyde  partially  decomposed,  the  hydrogen  contains  carbon  monoxide. 

PbO62 45(beginning) 

Mo2O3      54 

CdO 57  (beginning) 

Formaldehyde  almost  completely  destroyed,  the  gas  is  nearly  CO  +  2H2. 

Fe2O352 106  (beginning) 

V2O6     140 

SnO62 160  (beginning) 

Light  copper 152 

677.  The  dehydrogenating  power  of  oxides  can  hardly  be  explained 
except  by  assuming  an  unstable  combination  of  the  oxide  and  the 
aldehyde.53 

678.  Zinc  powder,  which  is  an  intimate  finely  divided  mixture  of 
metallic  zinc  and  zinc  oxide,  usually  containing  a  certain  proportion 
of   cadmium  and  cadmium  oxide,   acts   by  virtue  of  these  various 
substances  as  a  quite  active  dehydrogenation  catalyst,  particularly 
toward  methyl  alcohol,  the  formaldehyde  being  mostly  decomposed 
into  carbon  monoxide  and  hydrogen.    Long  ago  Jahn  noted  that  zinc 
powder  splits   methyl   alcohol   into   a   gas   containing  30%   carbon 
monoxide  and  70%  hydrogen.54 

12  The  gas  volumes  given  are  taken  after  the  absorption  of  the  carbon  dioxide 
resulting  from  the  slow  reduction  of  the  oxide. 

68  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  340  to  346  (1910). 
M  JAHN,  Berichte,  13,  983  (1880). 


679  CATALYSIS  IN  ORGANIC  CHEMISTRY  242 

679.  Carbon.    Baker's  coals  act  towards  alcohols  as  a  mixed  cata- 
lyst causing  dehydrogenation  and  dehydration  simultaneously. 

Ethyl   alcohol  undergoes   a   complex  reaction  at  375-385°,  being 
almost  completely  destroyed  yielding  methane  and  carbon  monoxide. 
With  isopropyl  alcohol  dehydration  predominates.55 

§  4.  — DEHYDROGENATION  OF  POLY-ALCOHOLS 

680.  Glycerine  is  the  only  poly-alcohol  of  which  the  dehydrogena- 
tion has  been  studied.     When  its  vapors  are  passed  at  330°  over  very 
light  reduced  copper,  prepared  by  the  reduction  of  cupric  carbonate  at 
a  low  temperature,  there  is  a  rapid  evolution  of  gas  consisting  of  hy- 
drogen mixed  with  methane,  carbon  monoxide  and  dioxide,  the  pro- 
portion of  the  latter  rising  to  one  third  of  the  whole. 

The  initial  effect  of  the  copper  is  dehydrogenation  to  glyceric 
aldehyde: 

CH2OH.CHOH.CH2OH  =  H2  +  CH2OH.CHOH.CHO. 

As  soon  as  this  is  formed  it  is  decomposed  in  the  same  way  as  it 
is  by  beer  yeast  into  ethyl  alcohol  and  carbon  dioxide: 56 

CH2OH.CHOH.CHO  =  C02  +  CH3.CH2OH. 

A  part  of  this  alcohol  is  found  in  the  distillate  and  a  part  suffers 
dehydrogenation  by  the  copper  to  acetaldehyde,  CH3.CHO,  which 
itself  splits  up,  more  completely  when  the  temperature  is  high,  into 
methane  and  carbon  monoxide. 

Furthermore,  at  the  temperature  of  the  reaction  a  portion  of  the 
glycerine  is  dehydrated  to  acrole'ine,  which  is  mostly  found  in  the  dis- 
tillate with  the  alcohol  and  water  but  a  part  of  which  is  hydrogenated 
by  the  copper  to  propionic  aldehyde,  allyl  alcohol  and  propyl  alcohol 
accompanied  by  condensation  products  due  to  the  crotonization  of  the 
aldehydes.  Ethyl  alcohol  is  the  chief  constituent  of  the  liquid.57 

§  5.  —  DEHYDROGENATION  OF  AMINES 

681.  Primary  Amines.    We  have  seen  that  nickel  permits  us  to  add 
hydrogen  to  nitriles  at  200°  to  form  primary  amines  (426).    We  may 
expect  that  it  will  reverse  this  reaction  at  higher  temperatures  and  take 
hydrogen  away  from  a  primary  amine  derived  from  a  primary  alcohol, 
to  reform  the  nitrile: 

R.CH2.NH2  =  2H2  +  R.CN. 

66  LEMOINE,  Butt.  Soc.  Chim.  (4),  3,  851  and  935  (1908). 
"  GRIMAUX,  Butt.  Soc.  Chim.  (2),  49,  251  (1888). 

67  SABATIEB  and  GAUDION,  Compt.  rend.,  166,  1037  (1918). 


243  DEHYDROGENATION  683 

This  is  what  takes  place  with  benzyl-amine,  with  amyl-amine  as 
well  as  with  other  primary  aliphatic  amines  derived  from  primary 
alcohols  having  at  least  five  carbon  atoms.68 

When  the  vapors  of  benzyl-amine  alone  are  passed  over  a  layer  of 
reduced  nickel  maintained  at  300-50°,  benzonitrile,  CeHB.CN,  is 
formed.  But  at  this  temperature  the  liberated  hydrogen  reacts  with 
the  amine  to  give  toluene  and  ammonia  (496),  so  that  the  evolution 
of  gas  is  a  minimum.  We  may  write  the  reaction: 

3C6H5.CH2.NH2  =  C6H5.CN  +  2C6H5.CH3  +  2NH3. 

The  yield  of  benzonitrile  is  about  one  third. 
Likewise  at  300°  isoamyl-amine  yields  isobutyl  cyanide  according  to 
the  reaction: 

3(CH3)2CH.CH2.CH2.NH2  =  (CH3)2CH.CH2.CN  +  2C6H12  +  2NH3. 

The  isopentane  produced  is  partially  destroyed  by  the  nickel,  de- 
positing carbon  and  liberating  hydrogen  and  lower  hydrocarbons. 

The  reaction  goes  poorly  with  amines  derived  from  primary  alco- 
hols having  less  than  five  carbon  atoms,  since  with  these  amines  nickel 
has  a  strong  tendency  to  eliminate  ammonia  with  the  formation  of 
ethylenic  hydrocarbons  (631). 59 

When  copper  is  used  in  place  of  nickel  between  390  and  400°, 
much  more  complex  products  are  obtained  somewhat  similar  to  those 
obtained  by  the  hydrogenation  of  aliphatic  nitro  compounds  (510). 

682.  Secondary  and  Tertiary  Amines.  Secondary  and  tertiary 
amines  derived  from  primary  alcohols  also  furnish  nitriles  when 
passed  over  nickel  at  320-50°,  by  the  simultaneous  elimination  of 
hydrogen  and  ethylenic  hydrocarbons.  Thus  from  di-isoamyl-amine 
and  tri-isoamyl-amine,  isobutyl  cyanide  is  obtained.60 


§  6.  —  SYNTHESIS  OF  AMINES 

683.  When  a  mixture  of  ammonia  and  benzene  vapor  is  heated  to 
550°  without  catalyst,  a  slight  formation  of  aniline  is  observed 
according  to  the  reaction : 61 

CA  +  NH3  =  H2  +  C6H6.NH2. 

68  SABATIER  and  GAUDION,  Cvmpt.  rend.,  165,  224  (1917). 

69  SABATIER  and  GAUDION,  Compt.  rend.,  165,  310  (1917). 

60  MAILHE  and  DE  GODON,  Compt.  rend.,  165,  557  (1917).  —  MAILHE,  Ibid.,  166, 
996  (1918). 

61  MEYER  and  TAUZEN,  Berichte,  46,  3183  (1913). 


684  CATALYSIS  IN  ORGANIC  CHEMISTRY  244 

With  hydrogen  in  presence  of  nickel  above  350°,  aniline  vapors 
regenerate  a  certain  amount  of  benzene  and  ammonia  by  the  reversal 
of  the  above  reaction  (496). 62 

It  might  be  hoped  that  the  direct  production  of  aniline  from  ben- 
zene vapor  and  ammonia  would  be  feasible  by  the  use  of  metal  cata- 
lysts at  500  to  700°.  It  has  been  found  that  the  presence  of  reduced 
nickel,  iron  or  copper  is  of  no  advantage,  as  only  traces  of  aniline 
are  produced.  Likewise  only  traces  of  toluidine  are  obtained  from 
toluene.  In  the  most  favorable  case  working  with  nickeled  asbestos  in 
an  iron  tube,  0.11  g.  aniline  was  obtained  from  200  g.  benzene.63 


§  7.  —  CLOSING  OF  RINGS  BY  LOSS  OF  HYDROGEN 

684.  Nickel.     Methyl-o. toluidine,  submitted  to  the  action  of  re- 
duced nickel  at  300-30°  (in  presence  of  hydrogen),  loses  hydrogen  to 
form  a  new  cycle,  yielding  above  6  %  of  indol  along  with  methane  and 
o.toluidine: 64 

/CH3  XCHV 

CeH/  ->     C6H/         )CH 

\NH.CH3  \NH/ 

Likewise  dimethyl-o. toluidine ,  at  300°,  yields  24%  of  N-methyl- 
indol  along  with  methane,  toluidine  and  methyl-toluidine: 65 

/CH3  XCH\ 

CeH/  ->    CeH/        >CH 

\N(CH3)2  \N.CH3 

685.  Aluminum  Chloride.     The  use  of  anhydrous  aluminum  chlo- 
ride at  moderate  temperatures,  between  80  and  140°,  causes  the  elim- 
ination of  hydrogen  with  the  formation  of  new  cycles. 

a-Dinaphthyl  yields  perylene: 66 


Likewise  at  140°,  meso-benzo-dianthrone  passes  quantitatively  into 
meso-naphtho-dianthrone: 87 

«  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  415  (1905). 
«  WIBAUT,  Berichte,  50,  541  (1917). 

64  CARBASCO  and  PADOA,  Lincei,  15  (2),  699  (1906). 

65  CARRASCO  and  PADOA,  Gaz.  Chim.  Ital.,  37  (2),  49  (1907). 

••  SCROLL,  SEER,  and  WELTZENBOCK,  Berichte,  43,  2203  (1910). 
•T  SCHOLL  and  MANSFIELD,  Berichte,  43,  1737  (1910). 


245  DEHYDROGENATION  686 


0  0 

At  140°  phenyl-a-naphthyl-ketone  gives  a  good  yield  of  benzanthrone: 

Q 


This  is  a  typical  example  of  many  analogous  reactions  that  can  be 
readily  carried  out  by  this  process.68 

686.  Metallic  Oxides.  Various  anhydrous  metallic  oxides,  alu- 
mina, ferric  oxide,  chromium  trioxide,  thoria,  and  titania  can  cause 
the  condensation  of  acetylene  with  various  molecules  with  the  elinv 
ination  of  hydrogen  and  the  formation  of  cyclic  compounds. 

With  ammonia  pyrrol,  picoline  and  collidines  are  formed,  there 
being  no  hydrogen  evolved  in  the  formation  of  the  latter: 

2C2H2  +  NH3  =  H2 
3C2H2  +  NH3  -  H2 

picoline 

4C2H2  +  NH8  =  C8HnN 

collidine 

Ferric  oxide  is  the  best  catalyst  for  forming  pyrrol. 

When  ethylene  is  used  instead  of  acetylene,  the  same  products  are 
formed  but  at  higher  temperatures  and  with  the  evolution  of  much 
hydrogen. 

Hydrogen  sulphide  gives  thiophene: 

2C2H2  +  H2S  =  H2  +  C4H4S. 
At  400-425°,  water  vapor  forms  furfural: 69 
2C2H2  +  H20  -  H2  +  C4H4O. 

"  SCROLL  and  SEER,  Sitz.  Akad.  Wien,  120,  11,  B,  925  (1911). —  ANN ALEN, 
394,  HI  (1912). 

"  CHICHIBABINE,  J.  Russian  Phys.  Chem.  Soc.,  47,  703  (1915),  C.  A.,  9,  2512 
1915). 


CHAPTER  XV 
DEHYDRATION 

687.  THERE  are  a  large  number  of  organic  reactions  which  take 
place  with  the  elimination  of  water.    Many  of  them  can  be  started  or 
accelerated  by  the  presence  of  so-called  dehydration  catalysts.     As 
might  be  anticipated  from  the  great  variety  of  reactions  of  this  kind, 
dehydration   catalysts   comprise  many  substances  of  very  different 
natures,  elements   (phosphorus,  carbon,  and   finely  divided   metals), 
strong  mineral  acids  (sulphuric,  hydrochloric,  phosphoric,  etc.),  either 
concentrated  or  dilute,  anhydrides  of  acids   (phosphoric  and  boric), 
anhydrous  chlorides  (of  aluminum,  zinc  and  iron),  various  inorganic 
salts  (ammonium  salts,  potassium  bisulphate,  calcium  and  aluminum 
sulphates,  phosphates,  etc.),  organic  acids    (acetic),  as  well  as  their 
salts  (potassium  and  sodium  acetates). 

We  can  distinguish  two  distinct  modes  of  dehydration  according 
to  whether  it  takes  place  in  the  gas  phase  by  the  action  of  solid  cata- 
lysts on  the  vapors  which  are  to  give  up  the  water  or  in  the  liquid 
medium.  We  will  study  the  two  separately. 

§  1.  — DEHYDRATION  OF  ALCOHOLS  ALONE 

688.  Primary  alcohols  can  undergo  dehydration  in  two  different 
ways :   to  produce  an  ether  or  a  hydrocarbon,  usually  unsaturated. 
Thus  with  ordinary  alcohol,  we  have : 

2CH3.CH2OH  =  H20  +  (CH3.CH2)2O 

ethyl  ether 

and  CH3 .  CH2OH  =  H2O  +  CH2 :  CH2. 

ethylene 

Benzyl  alcohol  gives : 

2C6H5.CH2OH  =  H20  +  (C6H6.CH2)2O 

benzyl  ether 

or  nC6H6CH2OH  =  nH2O  +  (C6H5.CH)n 


resinous  hydrocarbon 

Methyl  alcohol  is  an  exception,  as  it  can  be  dehydrated  regularly 
in  only  one  way,  that  is  to  form  methyl  ether,  (CH3)20. 

Secondary  alcohols,  the  dehydration  of  which  is  easier,  yield  ethers 
in  exceptional  cases  only  (e.g.  benzhydrol),  usually  producing  hydro- 
carbons. 

246 


247  DEHYDRATION  691 

The  ethers  can  seldom  be  obtained  from  tertiary  alcohols,  as  these 
are  dehydrated  to  the  hydrocarbons  with  still  greater  ease. 

689.  These  dehydrations  can  be  accomplished  by  a  multitude  of 
substances,  that  have  affinity  for  water,  used  in  excess  compared 
with  the  alcohol  that  is  to  be  dehydrated.     But  if  the   hydrates 
formed  are  unstable  at  the  temperature  of  the  operation,  water  is 
given  off,  regenerating  the  original  substance  which  can  repeat  the 
reaction  with  a  fresh  quantity  of  alcohol. 

This  is  what  takes  place  with  zinc  chloride  and  with  concentrated 
sulphuric  acid  of  which  a  small  quantity  when  heated  can  dehydrate 
a  large  amount  of  alcohol. 

We  have  explained  above  (159)  the  mechanism  of  the  action  of 
sulphuric  acid  which  produces  either  ethyl  ether  or  ethylene  from  alco- 
hol according  to  temperature  conditions.  It  can  continue  its  cata- 
lytic role  for  a  long  time,  but  is  gradually  diminished  by  being  reduced 
to  sulphur  dioxide,  since  it  slowly  oxidizes  the  alcohol  with  the  pro- 
duction of  carbon  dioxide  and  of  tarry  matters. 

Syrupy  phosphoric  acid  can  produce  an  entirely  analogous  effect, 
and,  as  it  is  less  readily  reduced  than  sulphuric  acid,  can  maintain  its 
catalytic  activity  for  a  much  longer  time..1'  2 

Formation  of  Ethers 

690.  The  formation  of  ethers  by  the  direct  dehydration  of  alcohols 
is  possible  in  only  a  small  number  of  cases  and  only  with  primary 
alcohols. 

In  the  case  of  methyl  alcohol  this  is  the  only  possible  manner  of 
dehydration  and  a  considerable  number  of  catalysts  can  decompose  its 
vapors  into  methyl  ether  and  water,  but  they  are  very  much  less 
numerous  than  the  substances  which  can  dehydrate  other  alcohols  to 
hydrocarbons. 

691.  Formation  in  Liquid  Medium.     Concentrated  sulphuric  acid 
is  usually  employed  to  dehydrate  methyl  alcohol  to  methyl  ether.s 

Zinc  chloride  is  not  suitable  for  this  reaction  as  it  gives  gaseous 
products  by  a  complicated  reaction  and  even  produces  a  certain 
amount  of  hexamethyl-benzene.* 

Ethyl  ether  is  practically  prepared  by  the  action  of  sulphuric  acid 
at  140*.  A  mixture  of  5  parts  of  90%  ethyl  alcohol  and  9  parts  of 

1  SABATIEK  and  MAILHE,  Bull.  Soc.  Chim.  (4),  1,  524,  (1907). 

2  This  is  used  for  preparing  ethylene  on  a  commercial  scale.  —  E.  E.  R. 

3  DUMAS  and  PELIGOT,  Ann.  Chim.  Phys.  (2),  68,  19  (1835). 

4  LE  BEL  and  GREENE,  Compt.  rend.,  87,  260  (1878).  —  Jahresber.  Chem.,  1878, 
388. 


692  CATALYSIS  IN  ORGANIC  CHEMISTRY  248 

concentrated  sulphuric  acid  is  used.  This  mixture  boils  at  about  140°. 
When  it  is  heated  to  140°,  ether  distils  over  and  alcohol  is  added  at 
such  a  rate  that  the  boiling  point  does  not  rise.  A  large  amount  of 
alcohol  can  be  transformed  into  ether  in  this  way.  The  volume  of  the 
ether  may  be  more  than  167  times  that  of  the  sulphuric  acid  used.5 
Theoretically  the  formation  should  continue  indefinitely,  but  the  yield 
decreases  after  a  certain  time  on  account  of  the  production  of  a  car- 
bonaceous residue  which  may  amount  to  5%  of  the  acid  and  the  for- 
mation of  which  corresponds  to  the  evolution  of  a  considerable  amount 
of  sulphur  dioxide. 

The  best  yield  of  ether  is  obtained  between  140  and  145°,  as  above 
that  temperature  more  and  more  ethylene  is  formed.6 

Phosphoric  or  arsenic  acid  may  replace  the  sulphuric  acid  in  this 
preparation.7  Anhydrous  zinc  chloride  also  may  be  used.8 

Concentrated  sulphuric  acid  at  135°  produces  propyl  ether  from  the 
alcohol  but  the  yield  is  poor  because  much  propylene  is  formed. 

The  higher  alcohols  such  as  isobutyl  do  not  yield  ethers  with  con- 
centrated sulphuric  acid  but  only  the  ethylenic  hydrocarbons.9  Never- 
theless, isoamyl  ether  can  be  thus  obtained  (696). 

Sometimes  sulphuric  acid  at  140°  enables  us  to  obtain  mixed  ethers 
by  operating  on  a  mixture  of  the  two  alcohols.  This  is  the  case  with 
methyl  and  ethyl  alcohols  which  yield  the  mixed  methyl-ethyl  ether 
along  with  the  two  simple  ethers.  In  the  same  way  ethyl-propyl  ether 
may  be  obtained,  but  ethyl-isobutyl  can  not  be.  Ethyl-isoamyl  ether, 
which  several  chemists  have  failed  to  obtain,10  can  be  prepared  along 
with  the  two  simple  ethers  by  the  action  of  85%  sulphuric  acid  at 
135-140°. " 

The  mixed  ethyl-tertiary-butyl  ether  can  be  obtained  by  heating  50 
volumes  of  a  mixture  of  two  molecules  of  ethyl  alcohol  and  one  of 
trimethyl-carbinol  with  one  volume  of  sulphuric  acid  in  a  sealed  tube 
at  100°  for  5  hours.12 

692.  Although  it  is  a  secondary  alcohol,  benzhydrol,  C6H5.CH(OH).- 
C6H5,  is  readily  transformed  into  its  ether:  it  is  sufficient  to  heat  it 
to  180°  with  27%  sulphuric  acid.13 

6  EVANS  and  SUTTON,  Jour.  Amer.  Chem.  Soc.,  36,  794  (1913). 

6  NORTON  and  PBESCOTT,  Amer.  Chem.  Jour.,  6,  243  (1884). 

7  BOULAY,  Gilbert's  Annalen,  44,  270  (1913). 

8  MASSON,  Annalen,  31,  63,  (1839). 

9  NORTON  and  PRESCOTT,  Amer.  Chem.  Jour.,  6,  244  (1884). 

10  GUTHRIE,  Annalen,  105,  37  (1858).  —  NORTON  and  PRESCOTT,  Amer.  Chem. 
Jour.,  6,  246  (1884). 

11  PETER,  Berichte,  32,  1419  (1899). 

12  MAMONTOFF,  J.  Russian  Phys.  C  em.  Soc.,  29,  234  (1897),  C.,  1897  (2),  408. 

13  ZAQUMENNI,  /.  Russian  Phys.  Chm.  Soc.,  12,  431  (1880),  C.,  1880,  629. 


249  DEHYDRATION  696 

The  ether  may  be  obtained  also  by  heating  benzhydrol  to  210- 
220°  with  finely  divided  copper.14 

693.  Formation  in  Gaseous  Phase.     Among  anhydrous  metallic 
oxides,  only  alumina  precipitated   and  dried  at  a  low  temperature 
effects    the    transformation    of    methyl    alcohol    into    methyl    ether 
exclusively.    The  reaction  commences  at  about  250°  and  is  rapid  at 
300°,  yielding  methyl  ether  which  can  be  completely  absorbed  by 
concentrated  sulphuric  acid.    At  about  350°  the  dehydration  is  accom- 
panied by  a  slight  dehydrogenation,  the  aldehyde  produced  being 
immediately  decomposed  into  carbon  monoxide  and  hydrogen. 

Thoria,  blue  oxide  of  tungsten  and  chromium  sesquioxide  can  dehy- 
drate methyl  alcohol  to  the  ether  above  230°  but  there  is  simultaneous 
dehydrogenation  to  the  aldehyde  and  its  decomposition  products. 
The  latter  reaction  is  still  more  important  with  titania  and  takes  place 
almost  exclusively  with  other  catalytic  oxides,  such  as  the  oxides  of 
zirconium,  molybdenum,  and  vanadium.16 

694.  Alone  among  the  oxides,  alumina  at  240°  enables  us  to  obtain 
ethyl  ether  from  ethyl  alcohol.     A  little  ethylene  is  evolved.     A  90% 
alcohol  may  be  used. 

With  propyl  alcohol  at  250°  it  gives  a  little  propyl  ether  but  forms 
propylene  chiefly.  It  can  not  produce  the  other  ethers.16  In  the 
apparatus  of  Ipatief,  under  high  pressures,  alumina  can  transform 
ethyl  alcohol  into  the  ether,  but  the  formation  is  limited  by  the  reverse 
reaction.  At  higher  temperatures  only  ethylene  is  produced.17 

Ethyl  ether  is  totally  decomposed  into  water  and  ethylene  by 
alumina  at  380°. 18 

Dehydration  to  Hydrocarbons 

695.  The  dehydration  of  a  single  molecule  to  give  a  hydrocarbon 
with  an  ethylene  double  bond  is  the  normal  reaction  of  alcohols  and 
also  of  ethers. 

Reaction  in  Liquid  Medium.  This  may  readily  be  accomplished 
by  concentrated  non-volatile  mineral  acids  and  also  by  anhydrous 
zinc  chloride. 

696.  Concentrated  Mineral  Acids.     A  small  proportion  of  con- 
centrated sulphuric  acid  used  at  a  temperature  high  enough  to  eliminate 
the  water  produced  serves  to  prepare  advantageously  the  lower  eth- 
ylenic  hydrocarbons  which  are  gases,  ethylene,  propylene,  and  butylene. 

14  KNOEVENAGEL  and  HECKEL,  Berichte,  36,  2823  (1903). 

16  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  345  (1910). 

16  SENDERENS,  Ann.  Chim.  Phys.  (8),  25,  449  (1912). 

17  IPATIEF,  Berichte,  37,  2961  (1904). 

18  ENGELDER,  J.  Phys.  Chem.,  21,  676  (1917). 


697  CATALYSIS  IN  ORGANIC  CHEMISTRY  250 

To  obtain  ethylene,  a  mixture  of  25  parts  of  alcohol  and  150  parts 
of  sulphuric  acid  is  heated  to  160-70°  and  a  mixture  of  alcohol  and 
sulphuric  acid  is  added  in  drops.19 

The  evolution  of  gas  is  facilitated  by  the  addition  of  a  certain 
amount  of  fine  quartz  sand  to  the  mixture.  According  to  Senderens, 
this  acts  as  a  true  chemical  catalyst.  According  to  the  same  author 
the  results  are  still  better  when  5%  of  anhydrous  aluminum  sulphate 
is  added  to  the  usual  mixture  of  alcohol  and  sulphuric  acid.  With 
ethyl  alcohol  at  157°  the  evolution  of  ethylene  is  thus  rendered  three 
times  as  rapid  and  propylene  is  formed  at  130°  instead  of  145°;  iso- 
butyl  alcohol  is  split  at  1250.20  21 

From  1500  cc.  isoamyl  alcohol  and  100  cc.  sulphuric  acid  in  a 
vessel  provided  with  a  reflux  condenser  kept  at  60-90°  followed  by  a 
condenser  for  the  amylene,  250  g.  of  amylene  (a  mixture  of  the  3 
isomers)  may  be  prepared  in  8  hours.  The  alcohol  remaining  in  the 
flask  contains  400  g.  isoamyl  ether.22 

Concentrated  phosphoric  acid  may  replace  sulphuric  acid  in  these 
dehydrations. 

697.  Under  analogous   conditions  the   dehydration  of  molecules 
with  mixed  function  may  be   catalyzed.     Thus   diacetonyl  alcohol, 
(CH3)2C(OH).CH2.CO.CH3,  warmed  with  traces  of  sulphuric  acid 
(6  drops  to  290  g.  of  the  alcohol),  furnishes  mesityl  oxide,  (CH3)2C  : 
CH.CO.CHa,  with  a  high  yield  (190  g.)  on  distillation.23 

698.  Zinc  Chloride.    Anhydrous  fused  zinc  chloride  is  very  often 
employed  to  effect  the  transformation  of  alcohols  into  ethylene  hydro- 
carbons, but  it  is  commonly  used  in  excess,  that  is  in  amount  more 
than  sufficient  to  fix  as  a  stable  hydrate  all  of  the  water  that  is 
eliminated.    The  same  action  can  be  exercised  by  the  catalyst  when 
the  alcohol  has  a  high  boiling  point  as  the  alcohols  of  the  cyclohexane 
series;   a  small  quantity  of  the  chloride  serves  to  dehydrate  these  to 
cyclohexenes  since  the  water  that  is  extracted  is  eliminated  by  dis- 
tillation along  with  the  hydrocarbon  so  that  the  catalyst  is  continu- 
ously regenerated. 

699.  Iodine.    In  exceptional  cases,  iodine  serves  to  effect  the  regu- 

19  ERLENMEYEB,  Annalen,  192,  244  (1878). 

20  SENDERENS,  Compt.  rend.,  151,  392  (1910). 

21  Following  the  observations  of  SENDERENS,  the  following  method  of  preparing 
ethylene  has  been  devised  and  has  given  excellent  service.    In  a  500  c.c.  flask  200 
c.c.  cone,  sulphuric  acid,  100  c.c.  95  %  alcohol  and  25  g.  of  dehydrated  alum  are 
heated  to  157  to  175°,  the  thermometer  dipping  in  the  mixture.     One  operator 
repeated  this  five  times  in  an  afternoon  and  obtained  667  g.  ethylene  bromide. 
—  E.  E.  R. 

22  ADAMS,  KAMM,  and  MARVEL,  Jour.  Amer.  Chem.  Soc.,  40,  1950  (1918). 
28  KOHN,  Monatsh.  Chem.,  34,  7T9  (1913). 


251  DEHYDRATION  702 

lar  dehydration  of  compounds  containing  alcohol  groups.  Diacetonyl 
alcohol,  (CH3)2C(OH).CH2.CO.CH3,  which  distillation  alone  breaks 
down  partially  into  two  molecules  of  acetone,  is  dehydrated  by  sul- 
phuric acid  to  mesityl  oxide  (697).  The  same  dehydration  takes  place 
quantitatively  when  it  is  distilled  with  a  small  amount  of  iodine.24 

700.  Reaction  in  Gaseous  System.     This  can  be  effected  by  a 
large  number  of  solid  catalysts  among  which  the  best  are  alumina, 
clay,  thoria  and  the  blue  oxide  of  tungsten. 

Elements.  Animal  charcoal,  extracted  with  hydrochloric  acid,  is  a 
rather  mediocre  catalyst  for  alcohols  :  above  350°  it  produces  ethylene 
from  ethyl  alcohol,  accompanied  by  a  certain  amount  of  methane,  car- 
bon monoxide  and  hydrogen  resulting  from  the  formation  of  acetal- 
dehyde  which  is  mostly  destroyed.  Propyl  alcohol,  above  300°,  gives 
a  gas  of  which  87  %  is  propylene,  with  ethylene  and  other  gaseous 
products.25 

Red  phosphorus  acts  more  rapidly  at  much  lower  temperatures  and 
probably  owes  this  activity  to  small  amounts  of  phosphorus  and 
phosphoric  acids  preexistent  in  the  material  and  which  are  formed  in 
considerable  amounts  in  consequence  of  the  oxidation  of  the  phos- 
phorus by  the  alcohol  with  a  correlative  production  of  phosphine. 

With  ethyl  alcohol  at  240°,  a  rapid  evolution  of  ethylene  is  obtained 
containing  5%  phosphine.  Similar  results  are  obtained  with  propyl 
alcohol.  The  proportion  of  phosphine  is  less  with  normal  and  iso-butyl 
alcohols  and  negligible  with  isopropyl  alcohol  which  is  already  split  at 
150°. 

The  presence  of  phosphine,  which  is  difficult  to  get  rid  of,  takes 
away  much  of  the  interest  in  this  case  of  catalysis. 

701.  Finely  divided  metals  have  an  important  catalytic  dehydro- 
genating  effect  on  primary  and  secondary  alcohols   (651);    but  they 
decompose  tertiary  alcohols  rapidly  at  moderate  temperatures  into 
unsaturated  hydrocarbons.     Reduced  nickel  acts  in  this  way  without 
complications  at  220  to  300°  and  reduced  copper  acts  similarly  above 
280  to  3000.26 

Passing  an  aliphatic  alcohol  over  copper  at  300°  is  a  simple  method 
of  determining  its  class.  A  primary  alcohol  forms  an  aldehyde,  a 
secondary  one  a  ketone,  while  a  tertiary  breaks  up  into  water  and  an 
unsaturated  hydrocarbon.27 

702.  Anhydrous  Metal  Oxides.    Grigoreff  in  1901  was  the  first  to 
note  the  special  aptitude  of  an  oxide  to  dehydrate  alcohols  :  he  found 

24  HIBBERT,  Jour.  Amer.  Chem.  Soc.,  37,  1748  (1915). 

25  SENDERENS,  Compt.  rend.,  144,  381  (1907). 

26  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  467  and  472  (1905). 

27  SABATIER  and  SENDERENS,  Bull.  Soc.  Chim.  (3),  33,  263  (1905). 


702 


CATALYSIS  IN  ORGANIC  CHEMISTRY 


252 


that  alumina  decomposes  ethyl  and  propyl  alcohols  to  the  hydrocar- 
bons with  90%  yields.28 

This  property  of  alumina  was  studied  by  Ipatief  and  found  also  in 
the  material  of  graphite  crucibles,  which  is  a  mixture  of  graphite 
(inactive)  and  clay,  while  other  oxides  (of  zinc,  iron,  tin,  chromium, 
etc.)  were  revealed  as  dehydrogenating  catalysts.29 

The  catalytic  activity  of  various  oxides  was  made  the  object  of  a 
thorough  study  by  Sabatier  and  Mailhe,30  who  were  able  to  demon- 
strate the  great  dehydrating  power  of  thoria  and  of  the  blue  oxide  of 
tungsten.  We  have  already  noted  (675)  that  the  oxides  that  are  not 
reducible,  or  only  slowly  reducible,  by  alcohols  can  be  divided  into 
dehydrogenating,  dehydrating,  and  mixed  catalysts  which  cause  both 
reactions  simultaneously. 

The  direction  and  the  importance  of  the  activity  of  the  various 
oxides  can  be  clearly  shown  by  a  comparison  of  the  volume  and  com- 
position of  the  gas  evolved  by  them,  when  equal  volumes  of  them  are 
used  at  340-50°  with  the  same  amount  of  ethyl  alcohol;  all  of  the 
oxides  having  been  prepared  below  350°  :31 


Dehydrating 


Mixed 


Dehydrogenating  < 


Oxide               gas 
ThO2  .... 

Volume  of 
in  cc.  per  min. 

.    .       31 

Composition 
C2H4%        H2% 

100           trace 
98.5            1.5 
98.5            1.5 

A1203  . 

.    .       21 

W205  .... 

.    .       57 

[Cr203     ... 

4.2 

91 
84 
63 

9 
16 
37 

Si02    .... 

0.9 

Ti02 

7.0 

BeO    .... 

1.0 

45 
45 

55 
55 

Zr02 

10 

UO2 

14 

24 
23 
14 
9 
5 

76 
77 
86 
91 
95 

Mo206    .    .    . 

5 

Fe203     .    .    . 

.       32 

14 

ZnO 

6 

[MnO  .... 
iMeO  . 

3.5 

traces 

0 
0 

100 
100 

28  GRIGOREFF,  /.  Russian  Phys.  Chem.  Soc.,  33,  173  (1901). 

29  IPATIEF,  Berichte,  34,  596  (1901);  35,  1047  (1902);  36,  1990  (1903). 

80  SABATIER  and  MAILHE,  Bull.  Soc.  Chim.  (4),  i,  107,  341,  524  and  733  (1907). 
—  Compt.  rend.,  146,  1376  (1908);  147,  16  and  106  (1908);  148,  1734  (1909).— 
Ann.  Chim.  Phys.  (8),  20,  289  (1910). 

81  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  341  (1910). 


253  DEHYDRATION  707 

703.  We  have  noted    (76)   that  the  physical  condition  and  the 
method  of  preparation  of  an  oxide  have  a  great  influence  on  its  ac- 
tivity and  even  on  the  direction  of  the  catalysis. 

These  differences  are  very  marked  for  the  various  varieties  of 
chromium  sesquioxide  (78)  the  only  one  of  which  that  is  suitable  for 
the  dehydration  of  alcohols  is  that  obtained  by  drying  the  precipitated 
blue  hydrated  hydroxide  below  350°. 

704.  Titanium  oxide,  TiO2,  prepared  by  calcining  at  a  red  heat 
has  very  little  activity.     To  obtain  a  suitable  oxide,  the  hydroxide 
prepared  by  the  action  of  ammonia  on  titanium  chloride  is  dehydrated 
below  3500.32 

705.  Crystallized    silica   is    almost    without    action    on    alcohols 
below    400°.     The    pure    silica    obtained    by    decomposing    silicon 
fluoride  by  water,  washing  thoroughly  and  drying  at   300°,   is   also 
only  slightly  active.     The  most  active  form  is  obtained  by  adding 
dilute    acid   to   sodium   silicate,   washing  and  drying  the  gelatinous 
precipitate. 

706.  The  most  active  form  of  alumina  is  prepared  by  precipita- 
tion from  aluminum  nitrate,  washing  the  precipitate  well  and  drying 
at  300°.     Good  results  are  also  obtained  with  the  oxide  prepared  by 
calcining  pure  ammonium  alum  at  red  heat.     The  basic  aluminum 
sulphate  obtained  by  calcining  aluminum  sulphate  at  a  dull  red  is  a 
very  active  catalyst.    On  the  contrary,  preparations  of  alumina  which 
have  been  heated  to  redness  for  a  long  time  are  almost  inactive  and 
sometimes   do   not   give  an  appreciable  amount   of  gas  from  ethyl 
alcohol  even  at  4200.33 

Bauxite,  aluminum  hydroxide  mingled  with  silica  and  ferric  hy- 
droxide, has  low  catalytic  power  and  dehydrogenates  chiefly  at  about 
4000.34 

The  nature  of  the  reaction  catalyzed  is  closely  connected  with  the 
condition  of  the  oxide  and  bears  a  certain  relation  to  its  ease  of 
solution  in  acids.35 

707.  Thoria,  on  the  contrary,  does  not  present  these  difficulties 
and  its  catalytic  activity  is  not  sensibly  diminished  by  calcination  at 

82  SABATIER  and  MAILHB,  Ann.  Chim.  Phys.  (8),  20,  325  (1910). 

88  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  300  (1910). 

54  Samples  of  bauxite  from  different  sources  differ  widely  in  catalytic  power. 
With  isoamyl  alcohol  a  sample  of  German  bauxite  gave  gaseous  products  but  poor 
yields  of  amylene,  while  a  Tennessee  sample  gave  little  gas  and  an  excellent  yield 
of  amylene.  The  bauxite  was  used  in  a  copper  tube  35  x  900  mm.  at  about  400°, 
the  alcohol  being  admitted  at  about  100  drops  per  minute.  Several  pounds  of 
amylene  were  thus  prepared.  —  C.  H.  Milligan. 

86  IPATIEF,  Berichte,  37,  2986  (1904). 


708  CATALYSIS  IN  ORGANIC  CHEMISTRY  254 

red  heat :  it  seems  that  its  high  molecular  weight  may  be  in  the  way 
of  molecular  condensations  such  as  alumina  appears  to  undergo  when 
heated  to  redness.36 

708.  There  are  great  differences  in  the  duration  of  the  catalytic 
activity  of  various  oxides;   usually  it  goes  on  decreasing  because  the 
surface  of  the  oxide  is  gradually  covered  by  small  amounts  of  tarry  or 
carbonaceous  matter  which  hinder  gaseous  exchanges  and  also  because 
molecular  condensations  take  place  in  the  oxides,  without  doubt,  even 
when  the  temperature  of  the  reaction  is  below  400°.     If  we  consider 
only  the  three  good  dehydration  catalysts,  alumina,  thoria,  and  the 
blue  oxide  of  tungsten,  alumina,  the  lightest  molecule   (Al20a,  molec- 
ular weight  92)  is  the  one  which  weakens  most  rapidly.    An  active 
specimen  which  disengaged  14  cc.  ethylene  per  minute  at  340°,  gave 
only  7  cc.  after  three  hours  of  use.37 

However  certain  observers  have  found  no  weakening  after  five 
hours.38  39 

The  blue  oxide  of  tungsten  is  much  more  permanent :  the  evolution 
of  gas  may  continue  for  several  hours  without  noticeable  weakening. 
The  same  is  true  of  thoria  which  has  the  great  additional  advantage 
of  being  very  readily  regenerated  when  long  usage  has  gummed  it  up ; 
calcining  at  a  red  heat  for  a  few  instants  is  sufficient  to  render  it 
perfectly  white  and  restore  its  original  activity.40 

709.  For  a  given  catalyst,  elevating  the  temperature  greatly  accel- 
erates the  reaction.     By  operating  under  the  same  conditions  with 
ethyl  alcohol   and  the   blue   oxide   of  tungsten,   it  has  been  found 
that  the  evolution  of  ethylene  begins  at  about  250°  and  becomes 
more   and   more    rapid    as   the   temperature   rises.     The    yield   per 
minute  was  : 


36  In  the  catalytic  preparation  of  mercaptans,  KRAMER  and  REID  (/.  Amer. 
Chem.  Soc.  43,  882  (1921))  find  that  the  activity  of  a  thoria  catalyst  depends  some- 
what on  the  temperature  to  which  it  has  been  subjected,  being  considerably  di- 
minished by  heating  much  above  400°.    Some  preparations  of  thoria  such  as  Wels- 
bach  gas  mantles  and  the  extremely  voluminous  product  obtained  by  dropping 
thorium  nitrate  into  a  red  hot  crucible  are  absolutely  inactive  so  far  as  this  reaction 
is  concerned.  —  E.  E.  R. 

37  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  299  (1910). 
88  ENGELDER,  /.  Phys.  Chem.,  21,  676  (1917). 

39  I  have  used  the  same  alumina  catalyst  for  many  days  in  making  ethylene 
without  noticing  any  deterioration.  —  E.  E.  R. 

40  A  thoria  catalyst  may  be  cleaned  by  passing  steam  over  it  at  380°  till  all 
volatile  material  is  removed  and  following  this  with  nitrogen  peroxide  at  the  same 
temperature  as  long  as  there  is  any  action,  the  oxides  of  nitrogen  being  finally 
displaced  by  steam.    A  catalyst  so  regenerated  is  snow  white  and  shows  its  origi- 
nal activity.  —  KRAMER  and  REID,  J.  Amer.  Chem.  Soc.  43,  884  (1921). 


255  DEHYDRATION  713 


Temperature 
260°                           

C.c.  per  minute 
5 

300°     

17.5 

310°     

...     27 

330°                     

48.5 

340°     

57.5 

370° 

73 

But  it  must  be  remembered  that  for  any  given  oxide,  the  elevation 
of  the  temperature  tends  to  introduce  and  make  more  and  more  prom- 
inent the  reaction  of  dehydrogenation.  Thus  at  340°  titania  produces 
practically  pure  ethylene  from  alcohol,  but  at  340°  with  a  more  rapid 
evolution  of  gas  there  is  some  hydrogen,  while  at  360°  the  hydrogen 
amounts  to  one  third  of  the  gas.41 

Above  400°  the  gas  produced  may  contain  ethane  along  with  the 
hydrogen.42 

710.  The  presence  of  water  in  the  alcohol  is  unfavorable  to  dehy- 
dration but  does  not  interfere   with  dehydrogenation.     Thus  with 
alcohol  diluted  with  its  own  volume  of  water,  alumina  gives  a  gas 
containing  twice  as  much  hydrogen  as  with  absolute  alcohol.42 

711.  Increase  of  pressure  retards  the  dehydration  of  alcohols,  or 
rather  raises  the  temperature  at  which  this  takes  place;    the  inter- 
mediate production  of  the  ether  from  primary  alcohols  is  favored  by 
increase  of  pressure  which  is  unfavorable  to  the  separation  of  the 
hydrocarbon.43 

712.  The  dehydration  of  alcohols  higher  than  propyl,  effected  by 
oxides  or  by  other  catalysts,  usually  leads  to  the  production  of  several 
isomeric  unsaturated  hydrocarbons  and  frequently  also  to  the  for- 
mation of  a  certain  proportion  of  polymers  (211). 

713.  Alumina.    The  best  results  are  obtained  with  alumina  precipi- 
tated from  aluminum  nitrate  by  ammonia,  well  washed  and  dried  at  300°. 

The  dehydration  of  methyl  alcohol  begins  at  about  250°  and  is 
rapid  below  300°,  yielding  exclusively  methyl  ether  absorbable  by  con- 
centrated sulphuric  acid.  At  about  350°,  the  ether  is  accompanied  by 
a  small  amount  of  aldehyde,  a  little  of  which  is  condensed,  and  hydro- 
gen is  collected  containing  carbon  monoxide  resulting  from  the  partial 
decomposition  of  the  formaldehyde. 

With  ethyl  alcohol,  ether  is  formed  above  240°  and  at  290°  pure 
ethylene  is  evolved  regularly,  this  evolution  becoming  rapid  at  340°. 

41  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  325  (1910). 

42  ENGELDER,  J.  Phys.  Chem.,  21,  676  (1917). 

43  IPATIEF,  J.  Russian  Phys.  Chem.  Soc.,  36,  786- and  813  (1904),  C.,  1904  (2), 
1020  and  38,  63  and  92  (1906),  C.,  1906  (2),  86  and  87. 


714  CATALYSIS  IN  ORGANIC  CHEMISTRY  256 

It  is  not  necessary  to  go  beyond  360°  where  the  ethylene  begins  to  be 
decomposed  and  where  its  evolution  slows  down  rather  rapidly  on 
account  of  the  weakening  of  the  catalyst.44 

Propyl  alcohol  gives  a  regular  current  of  propylene  above  300° 
without  any  of  the  ether. 

Normal  and  iso-butyl  alcohols  likewise  give  a  regular  evolution  of 
hydrocarbons  entirely  absorbable  by  sulphuric  acid.  Both  yield 
mixtures  of  the  isomeric  hydrocarbons,  C4H8.45  However,  Ipatief 
obtained  pure  isobutylene  from  isobutyl  alcohol.46 

With  isoamyl  alcohol,  the  dehydration  goes  readily,  the  best  yield 
being  obtained  between  500  and  540°.  The  product  contains  several 
isomeric  hydrocarbons,  CBHi0,  but  the  proportion  of  isopropyl-ethylene 
is  greater  than  in  the  dehydration  by  sulphuric  acid.47 

At  450°,  secondary  butyl  alcohol  gives  pure  butylene  and  tertiary 
butyl  alcohol,  or  trimethyl-carbinol,  yields  only  isobutylene.48 

At  a  dull  red,  allyl  alcohol  evolves  quite  pure  propylene  with  a  cor- 
relative production  of  acrole'ine.*9 

714.  Benzyl  alcohol  is  readily  dehydrated  at  above  300°  to  form 
the  yellowish  resinous   hydrocarbon    (C7H6)X,   without   evolution   of 
gas.50 

Other  primary,  secondary,  or  tertiary  aromatic  alcohols  are  read- 
ily dehydrated  by  alumina  without  complications  below  350°,  with  the 
production  of  the  corresponding  unsaturated  hydrocarbons.  Thus 
phenyl-benzyl-carbinol,  C6H5 .  CH  (OH) .  CH2 .  C6H5,  yields  stilbene,  C6H5 .  - 
CH:CH.C6H5,  quantitatively.51 

Borneol  gives  menthene  and  the  various  secondary  or  tertiary 
cyclohexyl  alcohols  are  readily  changed  to  the  corresponding  cyclohexene 
hydrocarbons.  Thus  cyclohexanol  is  entirely  transformed  into  cyclo- 
hexene and  1 .2-dimethyl-cyclohexanol  yields  1.2-dimethyl-cyclohexene.52 

At  350°  and  30  to  40  atmospheres  with  alumina,  decahydronaphthol 
yields  octahydronaphthalene,  CioHw,  boiling  at  197°. 53 

715.  Blue  Oxide  of  Tungsten.     Tungstic  oxide  is  readily  reduced 
by  alcohol  vapors  above  250°  and  brought  to  the  blue  oxide,  inter- 
mediate between  W03  and  WO2,  approaching  the  composition  W205 

44  SPRENT,  /.  Soc.  Chem.  Ind.,  32,  171  (1913). 
46  SENDERENS,  Bull  Soc.  Chim.  (4),  i,  692  (1907). 

46  IPATIEF  and  SDZITOWECKY,  Berichte,  40,  1827  (1907). 

47  ADAMS,  KAMM  and  MARVEL,  J.  Amer.  Chem.  Soc.,  40,  1950  (1918). 

48  IPATIEF  and  SDZITOWECKY,  Berichte,  40,  1827  (1907). 

49  KRESTINSKY  and  NIKITINE,  J.  Russian  Phys.  Chem.  Soc.,  44,  471  (1912). 

60  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  298  (1910). 

61  SABATIER  and  MURAT,  Ann.  Chim.  (9),  4,  284  (1915). 

62  IPATIEF  and  RUTALA,  /.  Russian  Phys.  Chem.  Soc.,  44,  1692  (1912). 
68  IPATIEF,  Berichte,  43,  3383  (1910). 


257  DEHYDRATION  717 

more  and  more  nearly,  and  which  on  exposure  to  the  air,  after  cooling, 
reoxidizes  spontaneously,  more  or  less  rapidly  regenerating  the  original 
yellow  oxide. 

This  blue  oxide  is  a  mediocre  catalyst  for  methyl  alcohol  which  it 
does  not  attack  till  330°,  dehydrating  and  dehydrogenating  it  simul- 
taneously, but  is  an  excellent  dehydration  catalyst,  very  active  and 
very  regular,  for  other  alcohols.54  By  using  a  train  of  blue  tungsten 
oxide  51  cm.  long  at  340°  and  vaporizing  17  g.  of  alcohol  per  hour  a 
regular  evolution  of  101  cc.  ethylene  per  minute  containing  only  1  or 
2%  of  hydrogen,  was  obtained,  5.1  g.  of  the  alcohol  escaping  decom- 
position. By  doubling  the  rate  of  flow  of  the  alcohol  the  evolution  of 
gas  reached  140  cc.  per  minute. 

At  320°,  propyl,  isobutyl  and  isoamyl  alcohols  give  good  yields  of 
the  unsaturated  hydrocarbons,  and  benzyl  alcohol  is  rapidly  trans- 
formed into  crusts  of  the  yellow  polymer  (714). 

716.  Thoria.    For  all  the  alcohols,  except  methyl,  thoria  is  a  very 
regular  catalyst,  the  properties  of  which  have  already  been  mentioned 
(708). 

With  ethyl  alcohol,  the  reaction  begins  around  280°  and  is  readily 
accelerated  by  rise  of  temperature.  By  using  a  boat  containing  4.7  g. 
thoria,  at  325°,  11  cc.,  and  at  350°,  31  cc.  of  practically  pure  ethylene 
were  obtained  per  minute. 

The  results  are  equally  good  with  propyl  and  isobutyl  alcohols  and 
with  the  other  alcohols  mentioned  under  alumina. 

The  secondary  alcohol,  isopropyl,  begins  to  yield  propylene  at  260°. 

717.  Mineral  Salts.    Clay,  or  hydrated  aluminum  silicate,  and  par- 
ticularly the  white  variety,   kaolin,  has  a  remarkable  dehydrating 
power  with  alcohols.55 

The  fragments  of  a  graphite  crucible  (a  mixture  of  graphite  and 
clay)  gave  Ipatief  a  good  yield  of  unsaturated  hydrocarbons  from 
alcohols.56 

In  1906,  Bouveault  noted  the  special  activity  of  clay  and  designed 
an  apparatus  for  using  it  for  the  dehydration  of  various  alcohols  quite 
similar  to  that  which  he  employed  for  their  dehydrogenation  over 
copper  (654).  The  catalyst  consisted  of  clay  balls  about  1  cc.  in 
volume,  dried  at  300°  in  a  current  of  air  and  packed  in  the  1  m.  ver- 
tical tube  of  the  apparatus  in  which  about  1  k.  of  alcohol  per  day 
could  be  dehydrated.  Ethyl,  propyl,  isobutyl  and  cyclohexyl  alcohols 

54  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  328  (1910). 
66  Kaolin  was  used  as  catalyst  in  preparation  of  ethylene  at  Edgwood  Arsenal, 
U.  S.  A.,  during  the  war.  —  E.  E.  R. 
6«  IPATIEF,  Berichte,  36,  1990  (1903). 


718  CATALYSIS  IN  ORGANIC  CHEMISTRY  258 

are  readily  dehydrated  by  this  means.  In  the  case  of  isoamyl  alcohol 
the  hydrocarbons  are  isomerized  as  with  alumina  or  zinc  chloride.57 
All  aluminum  salts  have  more  or  less  of  the  catalytic  power  of 
alumina.  The  basic  aluminum  sulphates  obtained  by  calcining  neutral 
aluminum  sulphate  at  a  dull  red  58  and  likewise  the  mixtures  of  these 
with  alkali  sulphates  obtained  by  calcining  potassium  and  sodium 
alums  have  this  power. 

718.  Calcium  sulphate  is  a  mediocre  catalyst.    When  obtained  by 
calcining  gypsum  at  a  moderate  temperature,  it  gives  with  alcohol  at 
420°  an  evolution  of  ethylene  containing  6  %  of  hydrogen,  while  if  it 
is  prepared  at  a  red  heat,  it  gives  a  very  slow  evolution  of  hydrogen 
containing  14  %  of  ethylene  at  4600.59 

719.  Aluminum  phosphate  is  recommended  as  a  good  catalyst  by 
Senderens,  who  explains  this  aptitude  as  a  sort  of  culmination  of  the 
catalytic  power  of  alumina  and  that  of  phosphorus.60    Ethyl  alcohol 
is  decomposed  above  330°  and  rapidly  at  380°.     With  propyl,  dehy- 
dration commences  at  300°  and  is  rapid  at  340°;   with  butyl,  the  re- 
action is  important  at  320°.    Isoamyl  alcohol  is  attacked  at  above  300°, 
while  250°  is  high  enough  to  decompose  isopropyl,  which  goes  rapidly 
at  300°.     The  decomposition  of  trimethyl-carbinol  begins  at  140°. 61 

720.  The  Case  of  Benzhydrol.    We  have  noted  above  (692),  that 
benzhydrol,  C6H5  •  CH  (OH)  •  C6H5,  heated  to  210°  with  copper  powder 
gives  the  ether,  ( (C6H6)2CH)2O,  in  75  %  yield  instead  of  benzophenone. 
At  a  higher  temperature,  290°,  copper  powder  produces  benzophenone 
chiefly  with  a  slow  evolution  of  hydrogen,  along  with  a  little  of  the 
ether  and  of  diphenylmethane.62 

In  fact  the  alcohol  is  dehydrogenated  to  benzophenone  but  the 
liberated  hydrogen  is  used  for  the  most  part  immediately  to  form 
diphenylmethane  and  particularly  symmetrical  tetraphenyl-ethane  : 

C6H5.CH(OH).C6H5  =  H2  +  C6H6.CO.C6H5 
C6H5.CO.C6H5  +  2H2  =  H20  +  C6H5 .  CH2 .  C6H5 
2C6H5.CO.C6H5  +  3H2  =  2H2O  +  (C6H5)2CH.CH(C6H5)2 

Dehydrating  catalysts  lead  to  the  same  result  as  copper.  The 
vapors  of  benzhydrol  passed  over  thoria  at  420°  give,  without  elimi- 
nation of  hydrogen,  a  mixture  of  benzophenone,  diphenylmethane  and 
sym.tetraphenyl-ethane  with  the  separation  of  water  simply.83 

67  BOTTVEAULT,  Bull.  Soc.  Chim.  (4),  3,  117  (1908). 

68  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  300  (1910). 

69  SENDERENS,  Bull.  Soc.  Chim.  (4),  3,  633  (1908). 

60  SENDERENS,  Bull.  Soc.  Chim.  (4),  i,  690  (1907). 

61  SENDERENS,  Compt.  rend.,  144,  1109  (1907). 

62  KNOEVENAGEL  and  HECKEL,  Berichte,  36,  2816  (1903). 
83  SABATIER  and  MURAT,  Ann.  Chim.  (9),  4,  282  (1915). 


259  DEHYDRATION  723 

721.  Catalytic  Passage  from  an  Alcohol  to  the  Corresponding 
Hydrocarbon.  This  passage  is  realized  easily  in  two  successive  steps  : 
1st  dehydration  of  the  alcohol  over  alumina  or  thoria  to  the  unsat- 
urated  hydrocarbon;  2nd  hydrogenation  of  this  hydrocarbon  over  a 
slightly  active  nickel  at  200-50°  : 


alcohol 


A  large  number  of  syntheses  of  hydrocarbons  in  this  way  have  been 
reported  by  Sabatier  and  Murat;  for  example,  uns.diphenyl-ethane 
(C6H5)2CH.CH3  was  prepared  from  methyl-diphenyl-carbinol,  (CeH^- 
C(OH).CI13.64 

722.  The  two  reactions  can  be  superimposed  by  submitting  the 
alcohols  to  the  simultaneous  action  of  alumina  and  nickel,  but  a  nec- 
essary condition  is  that  the  two  reactions  can  be  carried  on  at  the 
same  temperature  which  is  usually  impracticable  at  the  ordinary  pres- 
sure. They  can  be  readily  carried  on  simultaneously  in  the  apparatus 
of  Ipatief  (585).  Thus  fenchyl  alcohol  (40  g.)  with  alumina  (1.5  g.) 
and  nickel  oxide  (2.5  g.)  with  hydrogen  at  110  atmospheres  for  40 
hours  at  230°  gave  a  good  yield  of  fenchane,  boiling  at  162°,  and 
carvomenthol  gave  menthane. 

Camphor,  when  treated  under  the  same  conditions  at  220°,  is 
changed  into  isocamphene,  melting  at  63°.  The  succession  is  doubt- 
less :  65 


camphor  borneol 


Catalytic  Dehydration  of  Poly-alcohols 

723.  It  is  seldom  that  the  dehydration  of  poly-alcohols  leads  to 
hydrocarbons;  aldehydes  and  ketones  are  commonly  formed. 

However,  it  has  been  found  that  when  the  vapors  of  %-methyl- 
butane-diol(l  .3)  are  passed  over  kaolin  at  above  400°,  isoprene  is 
formed  :66 

HOCH2.CH(CH3)  .CH(OH)  .CH3  =  2H2O  +  CH2 :  C(CH3)  .CH  :  CH2. 

Quinite,  C6Hi0(OH)2,  submitted  to  the  action  of  alumina  at  350° 
and  30  to  40  atmospheres  pressure,  is  dehydrated  to  dihydro-benzene, 

64  SABATIER  and  MURAT,  Ann.  Chim.  (9),  4,  254  (1915). 

»  IPATIEF  and  MATOW,  Berichte,  45,  3205  (1912). 

•6  KYRIAKIDES  and  EARLE,  U.  S.  Patents,  1,094,222,  1,094,223  and  1,106,290. 


724  CATALYSIS  IN  ORGANIC  CHEMISTRY  260 


,  along  with  some  tetrahydro-phenol,  CeH9  .  OH,  resulting  from  the 
incomplete  dehydration.67 

724.  Glycol,  HOCH2.CH2OH,  heated  at  400°  with  alumina  yields 
chiefly  acetaldehyde  which  condenses  partially  to  paraldehyde. 

Pinacone,  (CHf)iC(OH).C(OH)(CHs),,  is  changed  at  300-20°  into 
pinacoline  as  it  is  by  the  action  of  dilute  sulphuric  acid.68 

725.  Glycerine   in   the   liquid   form   to   which   are   added   small 
amounts  of  alumina,  aluminum  sulphate  or  potassium  bisulphate,  is 
dehydrated  to  acroleiine  at  about  110°  : 

HOCH2.CH(OH)  .CH2OH  =  2H20  +  CH2  :  CH.CHO. 

To  100  parts  of  glycerine,  4  parts  anhydrous  aluminum  sulphate, 
8  parts  of  the  hydrated,  or  5  of  potassium  bisulphate  are  used.  The 
yield  is  17  to  19%,  or  a  little  smaller  than  when  227  parts  of  bisul- 
phate are  used  as  in  the  ordinary  method.69 

This  process  has  the  inconvenience  that  acetaldehyde  and  sulphur 
dioxide  are  evolved;  the  same  is  true  when  these  catalysts  are  re- 
placed by  ferric  or  cupric  sulphates. 

Better  results  are  obtained  with  anhydrous  magnesium  sulphate, 
with  which  more  than  50%  of  the  theoretical  yield  is  obtained  at 
330-40°,  with  negligible  amounts  of  by-products,  while  at  360°  acet- 
aldehyde appears.70 

726.  Dehydration  in  the  Gaseous  Phase.     When  the  vapors  of 
glycerine  are  passed  over  alumina  at  about  360°,  complete  dehydra- 
tion to  acrole'ine  takes  place,  but  a  portion  of  this  is  decomposed  into 
ethylene  and  carbon  monoxide  while  another  portion  is  crotonized  to 
higher  aldehydes  which  condense  along  with  the  water  and  acroleine.71 

When  for  the  alumina  catalyst  is  substituted  black  uranous  oxide, 
which  dehydrates  and  dehydrogenates  alcohols  at  the  same  time,  with 
a  predominance  of  the  latter  reaction  (675),  results  intermediate 
between  those  with  alumina  and  those  with  copper  (680)  are  obtained. 

By  using  kaolin  at  380-400°  or  aluminum  phosphate  at  450°  we  can 
transform  butane-diol  (1  .3)  into  butadiene  regularly  or  pentane-diol- 
(2.f)  into  piperylene.  The  presence  of  a  little  hydrobromic  add  or  of 
aniline  hydrobromide  increases  the  yield  which  for  piperylene  reaches 
50%. 

67  IPATIEP,  Berichte,  43,  3383  (1901).  —  J.  Russian  Phys.  Chem.  Soc.,  42,  1552 
(1911). 

68  IPATIEP,  J.  Russian  Phys.  Chem.  Soc.,  38,  92  (1906). 

69  SENDERENS,  Bull  Soc.  Chim.  (4),  3,  828  (1908).  —  Compt.  rend.,  151,  530 
(1910). 

70  WOHL  and  MYLO,  Berichte,  45,  2046  (1912).  —  WITZEMANN,  /.  Amer.  Chem. 
Soc.,  36,  1766  (1914). 

71  SABATIEE  and  GAUDION,  Compt.  rend.  166,  1034  (1918). 


261  DEHYDRATION  727 

Pinacone  is  likewise  dehydrated  to  dimethyl-butadiene  when  its 
vapors  are  passed  over  copper  at  430-500°  and  the  yield  is  raised  to 
70  %  by  the  presence  of  a  little  hydrobromic  acid.72 

727.  Ring  Formation  by  the  Dehydration  of  Poly-alcohols.  Long 
chain  molecules  containing  several  alcohol  groups  can  pass  into  the 
furfurane  ring  by  catalytic  dehydration  in  solution. 

Arabinose,  HOCH2.  CH  (OH)  .  CH  (OH)  .  CH  (OH)  .  CHO,  when 
boiled  with  sulphuric  acid  diluted  to  one  third,  is  converted  into 
furfural,™ 

CH CH 


-CHO 
\0/ 

Mudc  add  or  saccharic  add,  HOOC.  (CHOH)4.COOH,  heated  to 
100°  with  hydrochloric  acid,  loses  two  molecules  of  water  to  form 
dehydro-mudc  or  furfurane-dicarbonic  add  : 74 

CH CH 


HOOC/  \)/  \COOH 


72  KYRIAKIDES,  /.  Amer.  Chem.  Soc.,  36,  980  (1914). 
71  STONE  and  TOLLENS,  Annalen,  249,  237  (1888). 
74  YODER  and  TOLLENS,  Berichte,  34,  3446  (1901). 


CHAPTER  XVI 
DEHYDRATION  (Continued) 

§  2.  —  ELIMINATION  OF  WATER  BETWEEN  AN 
ALCOHOL  AND  A  HYDROCARBON 

728.  THE  use  of  anhydrous  aluminum  chloride  enables  us  to 
condense  an  aromatic  alcohol  with  an  aromatic  hydrocarbon  in  the  liquid 
phase.  Thus  benzyl  alcohol,  C6H5.CH2OH,  and  benzene  give  diphenyl- 
methane,  C&Hs .  CH2 .  CeH5,  accompanied  by  a  certain  amount  of  ortho 
and  para  dibenzyl-benzenes  and  other  hydrocarbons  among  which  is 
found  anthracene.1  The  same  reaction  takes  place  with  secondary 
aromatic  alcohols  which  yield  tertiary  hydrocarbons.  With  benzene 
we  have : 

/R 

C6H6 .  CH(OH) .  R  +  C6H6  =  H2O  +  C6H5 .  CH( 

\C6H5 

The  yield  is  better  when  R  is  an  aromatic  residue  than  when  it  is 
methyl  or  specially  ethyl.  The  use  of  an  excessive  quantity  of  alu- 
minum chloride,  particularly  if  the  temperature  is  high,  may  lead  to 
the  elimination  of  a  phenyl  group  or  of  an  aliphatic  residue,  R.2 

By  adding  aluminum  chloride  to  a  mixture  of  methyl-phenyl- 
carbinol,  C6H5 .  CH  (OH) .  CH3,  and  benzene  kept  at  25-35°,  a  20% 
yield  of  diphenyl-ethane  is  obtained  along  with  ethyl-benzene,  diphenyl- 
methane,  and  anthracene,  due  to  a  further  action  of  the  chloride.  By 
operating  at  10°  with  5  molecules  of  benzene  and  0.5  of  aluminum 
chloride  a  65  %  yield  of  diphenyl-ethane  is  obtained. 

Under  the  same  conditions,  ethyl-phenyl-carbinol  forms  diphenyl- 
propane  in  40  %  yield. 

Benzhydrol  dissolved  in  5  molecules  of  benzene  to  which  is  added 
1  molecule  of  aluminum  chloride  at  35-40°,  gives  a  40%  yield  of 
triphenyl-methane  with  some  diphenyl-methane.  By  operating  below 
10°,  the  yield  of  triphenyl-methane  reaches  65  to  70 %.8 

1  HUSTON  and  FRIEDEMANN,  J.  Amer.  Chem.  Soc.,  38,  2527  (1916). 

2  HUSTON  and  FRIEDEMANN,  J.  Amer.  Chem.  Soc.,  40,  785  (1918). 
8  HUSTON  and  FRIEDEMANN,  J.  Amer.  Chem.  Soc.,  40,  785  (1918). 

262 


263  DEHYDRATION  731 


§  3.  — ELIMINATION  OF  WATER  BETWEEN  AN  ALCOHOL 
AND  AMMONIA  OR  AMINES 

Reactions  in  Liquid  Systems 

729.  The  primary  aliphatic  alcohols  heated  for  several  hours  at 
220°  in  an  autoclave  with  aniline  and  a  very  small  amount  of  iodine 
as  a  catalyst,  give  good  yields  of  the  corresponding  alkyl-anilines.4 

Thus  by  heating  equal  molecules  of  aniline  and  methyl  alcohol  for 
9  hours  at  230°  with  1  %  of  iodine,  a  yield  of  73  %  of  methyl-aniline  is 
obtained.  By  using  2  molecules  of  the  methyl  alcohol,  86  %  of  dimethyl- 
aniline  is  obtained  in  7  hours  under  the  same  conditions. 

By  heating  1  molecule  of  aniline  and  4  molecules  of  ethyl  alcohol 
with  0.5  g.  iodine  10  hours,  95%  of  diethyl-aniline  is  obtained. 

Under  the  same  conditions,  benzyl  alcohol  and  aniline  give  benzyl-  or 
dibenzyl-aniline  and  isoamyl  alcohol  furnishes  amyl-  and  diamyl-anilines. 

With  alcohols  and  a  little  iodine,  a-  and  fi-naphthyl-amines  react 
similarly. 

730.  Aromatic  Alcohols  may  condense  with  aniline  or  its  homologs 
when  they  are  heated  gently  with  dilute  hydrochloric  acid.6    Thus  tet- 
ra-methyl-diamino-benzhydrol,  (CH3)2N .  C6H4 .  CH  (OH) .  C6H4 .  N  (CH3)2, 
eliminates  a  molecule  of  water  with  aniline  to  give  tetramethyl-leuc- 
aniline,  ( (CH3)2N .  C6H4)2CH .  C6H4 .  NH2. 


Reactions  in  Gaseous  Systems 

731.  We  have  seen  above  that  the  catalytic  dehydration  of  alco- 
hols by  various  anhydrous  metallic  oxides  has  been  explained  by 
Sabatier  and  Mailhe  on  the  assumption  of  the  formation  of  a  sort  of 
unstable  ester  between  the  alcohol  and  the  oxide  acting  as  an  acid, 
e.g.  an  alcohol  thorinate  (603). 

But  according  to  the  fundamental  method  of  Hofmann,  ammonia 
acts  on  the  esters  of  mineral  acids  to  form  amines.  Sabatier  and 
Mailhe  have  imagined  that  the  unstable  esters  formed  with  the  oxides 
should  behave  in  the  same  way.  It  was  to  be  hoped  that,  at  least  for 
some  oxides,  the  reaction  of  ammonia  with  the  temporary  ester  should 
be  more  rapid  than  the  decomposition  of  this  ester  into  an  ethylenic 
hydrocarbon.6 

4  KNOEVENAQEL,  J.  prakt.  Chem.  (2),  89,  30  (1914). 

6  BADISCHE,  German  Patent,  27,032  (1883). 

'  SABATIEB  and  MAILHE,  Compt.  rend.,  150,  823  (1910). 


732  CATALYSIS  IN  ORGANIC  CHEMISTRY  264 

Experiment  has  fully  verified  this  expectation.  Thus  with  thoria 
and  an  aliphatic  alcohol  we  have  : 

2CnH2n+1.OH  +  Th02  =  H20  +  ThO(OCnH2n+1)2 

thorinate 

Then: 

ThO(OCnH2n+1)2  +  2NH3  =  H2O  +  HCnH2n+1.NH2  +  ThO2 

amine  regenerated 

a  succession  of  reactions  which  is  equivalent  to  the  single  reaction  : 
CnH2n+1.OH  +  NH3  =  H20  +  CnH2n+1.NH2. 

amine 

732.  This  reaction  does  not  take  place  in  the  absence  of  a  catalyst, 
but  does  go  well  in  the  presence  of  thoria  at  300-50°,  the  dehydration 
into  an  unsaturated  hydrocarbon  being  only  a  side  reaction.  Thus  with 
ethyl  alcohol,  which  is  largely  broken  down  to  ethylene  by  thoria  at 
350°,  the  presence  of  ammonia  almost  completely  prevents  the  evo- 
lution of  the  hydrocarbon  but  causes  the  production  of  ethyl-amine. 
The  same  is  true  with  other  dehydrating  catalysts,  alumina,  blue  oxide 
of  tungsten  and  equally  with  the  mixed  catalysts,  such  as  titania, 
chromic  oxide,  blue  oxide  of  molybdenum,  zirconia,  etc.    The  formation 
of  the  amine  directs  the  activity  of  the  catalysts  to  its  profit :   the 
decomposition  of  alcohols  into  aldehydes  and  hydrogen  as  well  as  into 
water  and  ethylenic  hydrocarbons  is  almost  suppressed  and  the  for- 
mation of  the  amine  predominates. 

Furthermore  the  primary  amine  thus  produced  reacts  in  its  turn  on 
the  alcohol  in  the  presence  of  the  catalytic  oxide  as  does  ammonia, 
and  forms  the  secondary  amine: 

CnH2n+1.OH  +  CnH2n+1.NH2  =  H20  +  (CnH2n+1)2NH 

and  there  is  the  possibility  of  the  formation  of  some  tertiary  amine  by 
the  action  of  the  secondary  on  the  alcohol. 

733.  The  direct  action  of  ammonia  gas  on  alcohols  is  a  general 
method  for  the  preparation  of  amines.    Into  a  tube  containing  several 
grams  of  thoria  heated  below  350°  (from  250  to  350°  according  to  cir- 
cumstances) are  passed  at  the  same  time  alcohol  vapors  and  ammo- 
nia (furnished  very  conveniently  by  a  cylinder  of  liquid  ammonia). 
The  liquid  condensed  at  the  other  end  of  the  tube  is  a  mixture  of 
ammoniacal  water,  primary  and   secondary  amines    (with  traces  of 
tertiary)  and   untransformed   alcohol   holding  in  solution   a   certain 
amount  of  the  ethylenic  hydrocarbon.    The  latter  products  are  easily 
separated  from  the  amines  by  fractional  distillation.7 

From  propyl  alcohol,  mono-  and  dipropyl-amines  can  be  readily 
prepared  and  mono-  and  dwsoamyl-amines  from  isoamyl  alcohol. 
7  SABATIER  and  MAILHE,  Compt.  rend.,  148,  898  (1909). 


265  DEHYDRATION  738 

734.  Likewise  benzyl  alcohol  and  ammonia  with  thoria  at  300-350° 
give  only  a  small  amount  of  the  resinous  hydrocarbon  (C7H6)X,  but 
yield   chiefly  benzyl-  and  dibenzyl-amines,   and   a   small  amount   of 
tribenzyl-amine,  which  solidifies  in  the  condenser  tube.    By  operating 
at  330°,  benzyl-amine  is  the  main  product,  while  at  370-380°,  dibenzyl- 
amine  predominates,  but  there  is  at  this  temperature  a  notable  decom- 
position of  the  alcohol  to  the  aldehyde,  which,  in  turn,  is  split  into 
benzene  and  carbon  monoxide.8 

735.  The  secondary  alcohol,  isopropyl,  does  not  suffer  appreciable 
dehydration  over  thoria  at  250°,  but  at  that  temperature  ammonia  is 
effective  and  gives  about  20  %  of  isopropyl-amine  accompanied  by  a 
little  di-isopropyl-amine.     Around  300°  a  considerable  evolution  of 
propylene  is  observed  and  the  condensed  liquid  contains  about  one 
third  isopropyl-amine  and  about  the  same  amount  of  secondary,  along 
with  water  and  unchanged  alcohol.9 

Likewise  diethyl-carbinol  and  dipropyl-carbinol  give  mixtures  of  the 
corresponding  primary  and  secondary  amines.10 

736.  The  method  is  less  easy  to  apply  to  benzhydrol:    yet  its 
vapors  when  carried  by  an  excess  of  ammonia  over  thoria  at  280°  give 
some    benzhydryl-amine,    but    dehydration    preponderates    producing 
tetraphenyl-ethylene. 

737.  The   secondary  cyclohexane  alcohols    (cyclohexanol  and  its 
homologs)  are  dehydrated  rapidly  in  contact  with  thoria  at  300-350° 
but  in  the  presence  of  ammonia  at  290-320°  the  reaction  is,  for  the 
most  part,  directed  toward  the  formation  of  amines,  hardly  more  than 
30  to  40%  of  the  unsaturated  hydrocarbons  being  simultaneously 
produced. 

In  this  way  cyclohexyl-amine  and  the  three  methyl-cyclohexyl- 
amines  have  been  prepared,  some  of  the  secondary  amines  being 
formed  in  all  cases.11 

738.  Mixed  Amines.     In  this  reaction  the  ammonia  may  be  re- 
placed by  a  primary  aliphatic  amine  which  gives  us  a  method  of 
preparing  mixed  secondary  amines.    It  is  sufficient  to  pass  a  mixture 
of  a  primary  amine  and  an  aliphatic,  aromatic,  or  cyclohexyl  alcohol 
in  equivalent  amounts  over  thoria  at  about  320°.    Among  the  aliphatic 
alcohols,  methyl  gives  the  poorest  results.     Ethyl-isoamyl-amine,  boil- 
ing at  126°,  propyl-isoamyl-amine,  boiling  at  145°,  and  isobutyl-isoamyl- 
amine,  boiling  at  158°,  have  been  prepared  in  this  manner.12 

8  SABATIER  and  MAILHE,  Compt.  rend.,  153,  160  (1911). 

9  SABATIER  and  MAILHE,  Compt.  rend.,  153,  1204  (1911). 

10  MAILHE,  Bull.  Soc.  Chim.  (4),  15,  327  (1914). 

11  SABATIER  and  MAILHE,  Compt.  rend.,  153,  1204  (1911). 

12  SABATIER  and  MAILHE,  Compt.  rend.,  148,  900  (1909). 


739  CATALYSIS  IN  ORGANIC  CHEMISTRY  266 

739.  By  associating  cyclohexyl-amine  with  various  aliphatic  alco- 
hols, with  benzyl  alcohols,  and  with  cyclohexanol  and  its  homologs,  a 
large  number  of  mixed  secondary  cyclohexyl-amines  can  be  prepared.13 

Thus  methyl  alcohol  gives  methyl-cyclohexyl-amine,  boiling  at  145°, 
while  ethyl  and  other  primary  alcohols  give  the  corresponding  mixed 
amines  with  still  better  yields.  Isopropyl-cyclohexyl-amine 14  and 
benzyl-cyclohexyl-amines  have  been  made  thus. 

Cyclohexanol  itself  gives  di-cyclohexyl-amine  identical  with  that  ob- 
tained in  the  hydrogenation  of  aniline  (466).  The  three  methylcyclo- 
hexanols  give  the  three  methylcyclohexyl-cyclohexyl-amines.15 

740.  At  higher  temperatures  the   aromatic  amines  can  undergo 
similar  reactions.    By  passing  over  alumina  at  400-430°  a  mixture  of 
aniline  vapors  and  methyl  alcohol  in  excess,  the  immediate  formation 
of  methyl-aniline  is  obtained  and  of  dimethyl-aniline ,  resulting  from  the 
action  of  the  methyl  alcohol  on  the  methyl-aniline. 

Likewise  o.toluidine  is  completely  transformed  by  methyl  alcohol 
over  thoria  into  methyl-o.toluidine  and  then  into  dimethyl-o.toluidine. 
Similar  results  are  obtained  with  meta  and  para  toluidines.  A  single 
passage  over  the  catalyst  produces  about  equal  proportions  of  the 
mono-  and  di-methyl  compounds,  and  a  second  passage  completes  the 
substitution.16 

By  causing  ammonia  to  act  on  a  mixture  of  two  alcohols,  the  pri- 
mary and  secondary  amines  corresponding  to  each  alcohol  are  obtained 
and  some  of  the  mixed  secondary  amine.  This  has  been  found  true 
with  a  mixture  of  propyl  and  isoamyl  alcohols  at  330°. 

741.  Alkyl-piperidines.     The  above  method   can  be  applied  to 
piperidine  with  various  alcohols  over  thoria  at  350°.    The  results  are 
satisfactory  with  propyl  alcohol  which  yields  only  a  little  propylene 
and  gives  N-propyl-piperidine}  boiling  at  149°,  and  with  isoamyl  alco- 
hol which  furnishes  N-isoamyl-piperidine,  boiling  at  186°,  but  are  poor 
with  cyclohexanol  which  gives  much  cyclohexene  and  only  a  little 
N-cyclohexyl-piperidine,  boiling  at  216°. 17 

742.  Pyrrol.      An  analogous  reaction  is  carried  out  by  the  aid  of 
zinc  dust  with  a  mixture  of  ethyl  alcohol  and  pyrrol  which  give  a-ethyl- 
pyrrol.1* 

13  SABATIEE  and  MAILHE,  Compt.  rend.,  153,  1207  (1911). 

14  MAILHE  and  AMOROUX,  Bull  Soc.  Chim.  (4),  15,  777  (1914). 

15  SABATIER  and  MAILHE,  Compt.  rend.,  153,  1207  (1911). 

16  MAILHE  and  DE  GODON,  Compt.  rend.,  166,  467  and  564  (1918). 

17  GAUDION,  Bull  Soc.  Chim.  (4),  9,  417  (1911). 

18  DENNSTEDT,  Berichte,  23,  2563  (1890).  — ZANETTI,  Gaz.  Chim.  Ital,  21  (2), 
167  (1891). 


267  DEHYDRATION  744 


§  4.  —  ELIMINATION   OF  WATER  BETWEEN  AN 
ALCOHOL  AND  HYDROGEN  SULPHIDE 

Synthesis  of  Mercaptans 

743.  If  the  direct  action  of  alcohols  on  the  dehydrating  oxides, 
such  as  thoria,  gives  rise  to  the  formation  of  a  sort  of  unstable  ester 
(thorinate),  it  can  be  predicted  that  when  this  is  brought  into  contact 
with  an  acid  more  energetic  than  the  hydrate  of  the  oxide,  such  acid 
will  displace  the  oxide  at  least  in  part  to  give  a  new  ester.    We  will 
have: 

ThO(OCnH2n+1)2  +  2AH  =  2A.CnH2n+1  +  ThO2  +  H2O 

thorinate  ester 

and  if  the  acid  is  incapable  of  forming  a  stable  salt  with  thoria  as  a 
base,  the  thoria  will  be  regenerated  and  will  react  with  a  new  portion 
of  alcohol  to  repeat  the  cycle. 

Sabatier  and  Mailhe  believed  that  hydrogen  sulphide,  which  does 
not  react  with  thoria  (nor  with  alumina),  would  act  in  this  manner, 
since  it  appears  to  be  a  stronger  acid  than  thoria.  We  would  have 
in  succession: 

ThO(OCnH2n+1)2  +  2H2S  =  2CnH2n+1.SH  +  ThO2  +  H2O 

""          thorinate  mercaptan 

and  then,  with  greater  difficulty,  on  account  of  the  acid  function  still 
remaining  in  the  mercaptan: 

ThO(OCnH2n+1)2  +  2CnH2n+1.SH  =  2(CnH2n+1)2S  +  Th02  +  H20. 

thorinate 

The  thoria  being  regenerated  can  react  with  a  fresh  portion  of 
alcohol  and  if  the  hydrogen  sulphide  continues  to  act,  the  thoria  can 
function  indefinitely  as  a  catalyst  to  produce  mercaptans  and  alkyl 
sulphides,  provided  that  the  reaction  of  the  hydrogen  sulphide  on  the 
unstable  thorinate  is  more  rapid  than  the  decomposition  of  the  tho- 
rinate into  the  unsaturated  hydrocarbon,  water  and  thoria. 

744.  Experiment  has  shown  that  this  is  usually  the  case.    This  is 
a  direct  method  for  the  preparation  of  mercaptans  from  the  alcohols. 
It  is  sufficient  to  pass  a  mixture  of  the  alcohol  vapors  and  hydrogen 
sulphide  over  a  train  of  thoria  maintained  between  300  and  380°. 
The  mercaptan  along  with  a  small  amount  of  the  neutral  sulphide  is 
condensed  with  the  water  and  unchanged  alcohol. 

A  portion  of  the  alcohol  is  dehydrated  to  the  unsaturated  hydro- 


745  CATALYSIS  IN  ORGANIC  CHEMISTRY  268 

carbon,  but  with  the  primary  aliphatic  alcohols  this  is  not  important, 
provided  the  reaction  temperature  is  not  too  high,  but  it  is  consid- 
erable with  the  secondary  alcohols  which  decompose  into  hydrocarbons 
more  readily. 

Methyl,  ethyl,  propyl,  isdbutyl,  and  isoamyl  mercaptans  have  been 
thus  prepared  with  yields  above  75  %,  so  long  as  the  condensation  of 
the  products  is  efficient.  The  yield  is  equally  good  for  allyl  mercaptan 
from  allyl  alcohol.  Benzyl  alcohol  gives  a  rather  large  proportion  of 
benzyl  mercaptan  and  some  sulphide.1920 

745.  The  yields  are  less  satisfactory,  hardly  above  one  third,  when 
secondary  alcohols  are  used.    The  following  mercaptans  have  been  ob- 
tained in  this  way:  propane-thiol(2),  pentane-thiol(3),  heptane-thiol(5), 
%.4-dimethyl-pentane-thiol(8),  cyclohexyl  mercaptan  and  the  three  o.m. 
and  p.methyl-cyclohexyl  mercaptans?1  and  also  the  mercaptan  from  benz- 
hydrol,  C6H5.CH(SH).C6H5,  boiling  at  2780.22 

746.  Various  other  catalytic  oxides  have  been  found  to  be  inferior 
to  thoria.     With  isoamyl  alcohol  and  thoria  maintained  at  370-80°, 
the  approximate  yields  of  mercaptans  for  100  parts  of  alcohol  de- 
stroyed were: 

Thoria 70 

Zirconia      44 

Uranous  oxide 30 

Blue  oxide  of  tungsten 22 

Chromic  oxide 18 

Blue  oxide  of  molybdenum 17 

Alumina 10 

Alumina  gives  amylene  chiefly.23 

19  SABATIER  and  MAILHE,  Compt.  rend.,  150,  1217  (1910). 

20  Working  at  360-380°  KRAMER  and  REID  \_J.  Amer.  Chem.  Soc.  43,  887  (1921)], 
obtain  the  following  yields  from  the  alcohols  named:  methyl  42  %,  ethyl  35  %, 
propyl  45  %,  n.butyl  52  %,  isobutyl  36  %,  isoamyl  42  %.     A  part,  at  least,  of  the 
discrepancy  between  these  figures  and  those  given  by  Sabatier  and  Mailhe  is  due 
to  a  different  method  of  estimating  the  mercaptan  produced. 

They  find  that  the  amounts  of  unsaturated  hydrocarbons  formed  are  surprisingly 
low,  usually  only  2  to  3  %,  while  considerable  amounts  of  the  aldehydes,  7  to  15  % 
(estimated  by  the  hydrogen  produced),  are  formed.  —  E.  E.  R. 

21  MAILHE,  Bull.  Soc.  Chim.  (4),  15,  327  (1914). 

22  SABATIER  and  MAILHE,  Butt.  Soc.  Chim.  (4),  u,  99  (1912). 

23  SABATIER  and  MAILHE,  Compt.  rend.,  150,  1569  (1914). 


269  DEHYDRATION  750 


§  5.  — ELIMINATION  OF  WATER  BETWEEN  ALCOHOLS 

AND  ACIDS 

Esterification 

747.  It  is  known  that  the  formation  of  esters  by  the  direct  action 
of  organic  acids  on  alcohols  takes  place  very  slowly  at  ordinary  tem- 
peratures and  that  the  transformation  is  never  complete  as  it  is  limited 
by  the  inverse  action  of  water  on  the  ester.    Several  years  of  contact 
are  required  for  this  limit  to  be  reached.     Elevation  of  the  tempera- 
ture hastens  the  reaction  greatly  but  it  still  requires  considerable  time, 
several  days  at  110°,  several  hours  at  156°. 

The  production  of  ester  is  very  slow  in  the  gaseous  state  also,  even 
at  temperatures  above  250°:  when  a  mixture  of  equivalent  amounts 
of  the  vapors  of  ethyl  alcohol  and  acetic  acid  is  passed  through  a  tube 
heated  above  250°,  the  esterification  effected  is  entirely  negligible. 

But  either  in  the  liquid  or  in  the  vapor  condition,  the  presence  of 
small  amounts  of  catalysts  accelerates  the  production  of  ester  enor- 
mously so  that  the  limit  is  soon  reached. 

Esterification  by  Catalysis  in  the  Liquid  State 

748.  The  catalysts  for  esterification  in  liquid  system  are  chiefly  the 
strong  mineral  adds,  hydrochloric  and  sulphuric,  and  several  salts, 
ammonium  salts,  alkaline  bisulphates,  zinc  chloride,  sodium  acetate  mixed 
with  water. 

749.  Catalysis  by  Mineral  Acids.    When  equal  molecules  of  ethyl 
alcohol  and  acetic  acid  are  mixed  and  the  mixture  is  distilled,  the 
amount  of  ester  produced  is  less  than  1  %. 

But  a  long  time  ago,  Berthelot  found  that  it  is  sufficient  to  add  to 
a  mixture  of  an  organic  acid  and  an  alcohol  a  few  per  cent  of  hydro- 
chloric or  sulphuric  acid  to  cause  an  abundant  formation  of  ethyl 
acetate,  benzoate,  etc.24  He  showed  that  traces  of  sulphuric  acid  are 
sufficient  for  the  preparation  of  ethyl  acetate.26 

750.  To  a  mixture  of  equal  molecules  of  ethyl  alcohol  and  acetic 
acid    (106   g.)    small   quantities   of   hydrochloric   acid   were   added, 
namely : 

To  the  first  0.67  g.  or  0.017  molecule 

second  4.77  g.  or  0.125  molecule 

third  11.84  g.  or  0.33    molecule 

24  BERTHELOT,  Butt.  Soc.  Chim.  (2),  31,  342  (1879). 

26  BERTHELOT  and  JUNGFLEISCH,  Traitt  de  Chim.  Organ.,  3rd  Ed.  1886,  I,  208. 


761  CATALYSIS  IN  ORGANIC  CHEMISTRY  270 

The  amounts  of  ester  formed  were  as  follows : 

At  ordinary  temperature 
First        Second        Third 

Immediately  after  mixing          9.6  %       58.7  %        82.3  % 
After  six  hours  9.6  73.6  75.8 

The  limit  without  the  mineral  acid  would  be  66.6  % :  this  limit  is 
raised  by  the  presence  of  the  hydrochloric  acid,26  and  is  practically 
attained  in  six  hours  with  the  above  mixtures.  In  the  cold,  without 
this  acid,  several  years  would  have  been  required.  Besides,  no  ethyl 
chloride  was  formed. 

751.  Analogous  results  were  obtained  with  sulphuric  acid.     To  a 
mixture  of  1  mol.  ethyl  alcohol,  1  mol.  acetic  acid  and  0.5  mol.  water 
was  added  0.02  mol.  (about  2  g.)  sulphuric  acid  and  in  24  hours  in  the 
cold,  the  esterification  had  reached  59.6  %.    In  2  hours  at  100°,  60.6  % 
was  reached,  which  is  the  limit  for  this  system.27 

By  boiling  under  reflux  a  mixture  of  25  cc.  propionic  acid,  25  cc. 
propyl  alcohol,  and  50  cc.  5%  sulphuric  acid,  the  proportion  of  ester 
was : 28 

After  0.5  hour 45.1  % 

1  hour 51.8 

2  hours 56.9 

3  hours 58.3 

752.  The  action  of  the  sulphuric  acid  can  be  explained  by  the  for- 
mation of  acid  ethyl  sulphate,  the  immediate  product  of  the  action  of  the 
sulphuric  acid,  and  the  action  of  which  on  the  acetic  acid  would  pro- 
duce ethyl  acetate  and  regenerate  sulphuric  acid,  which  would  renew 
the  action.     In  the  case  of  hydrochloric  acid,  Berthelot  explains  the 
accelerating  action  by  assuming  the  formation  of  an  addition  product 
of  the  hydrochloric  acid  and  the  alcohol.29  30 

Bodroux  has  proposed  a  different  explanation  based  on  the  tem- 
porary formation  of  an  addition  compound  of  the  mineral  acid  cata- 

26  BERTHELOT  explained  the  elevation  of  the  limit  by  the  taking  part  of  the 
hydrochloric  acid  in  the  equilibrium,  in  which  it  increases  the  total  amount  of  acid 
relative  to  the  alcohol. 

27  BERTHELOT,  Bull.  Soc.  Chim.  (2),  31,  342  (1879). 

28  BODROUX,  Compt.  rend.,  157,  939  (1913). 

29  BERTHELOT,  Bull  Soc.  Chim.  (2),  31,  342  (1879). 

30  It  is  curious  how  many  chemists  have  given  entirely  different  explanations 
for  the  action  of  hydrochloric  and  sulphuric  acids.    All  the  facts  go  to  show  that 
all  acids  act  alike  and  that  whatever  explanation  is  given  in  any  one  case  must  fit 
all  others.  — E.  B.  R. 


271  DEHYDRATION  755 

lyst  with  the  organic  acid  considered  as  the  anhydride  of  an  ortho 
acid: 

M  /OH 

AH  +  R.cf        =  R.C—  OH 
\OH  \A 

/OH  /OH 

then  :  R  ,  Cf-OH  +  R'OH  =  AH  +  R  .  C—OH 

\A  \OR' 

and  finally  by  the  immediate  spontaneous  loss  of  water:31 


R.C  =  H20  +  R.CO.OR'. 

\OR' 

753.  Many  chemists  still  continue  to  think  that  the  presence  of  a 
large  amount  of  the  mineral  acid  is  favorable  to  esterification  and  it 
has  become  common  usage  to  saturate  the  mixture  of  alcohol  and  acid 
with  hydrogen  chloride  when  preparing  esters.     Many  seem  to  have 
forgotten  that  the  same  end  can  be  attained  by  employing  very  small 
proportions  of  acids  as  catalysts.     In  1895  Emil  Fischer  and  Speier 
made  exact  measurements  on  this  matter  and  showed  that  the  use  of 
small  quantities  of  the  mineral  acids  makes  the  operation  more  con- 
venient and  leads  to  satisfactory  yields.32 

754.  Thus   for   the   preparation   of   ethyl   benzoate,   the   classical 
method  was  to  saturate  with  hydrogen  chloride  a  mixture  of  1  part  of 
benzoic  acid  with  4  parts  ethyl  alcohol,  which  gave  only  73  %  yield. 
Erdmann  recommended  heating  on  the  water  bath  for  10  to  12  hours 
1  part  of  the  acid,  0.8  of  alcohol  and  0.4  of  concentrated  sulphuric 
acid,  the  yield  being  75%. 

By  dissolving  3%  hydrogen  chloride  in  a  mixture  of  2  parts  of 
alcohol  to  1  part  of  acid,  Emil  Fischer  obtained  76%  of  the  ester, 
while  for  1  %  hydrogen  chloride,  the  yield  was  64.5  %  for  the  same 
time  of  heating. 

755.  The  use  of  sulphuric  acid  is  very  advantageous.    A  mixture 
of  1  part  of  benzoic  acid,  2  parts  of  alcohol  and  0.2  part  concentrated 
sulphuric  acid  as  heated  3  hours  under  reflux  and  a  practical  yield  of 
90%  is  obtained.    If  account  is  taken  of  inevitable  losses  during  the 
washings,  the  yield  is  practically  quantitative  and  as  the  excess  of 
alcohol  can  be  recovered  almost  entirely,  the  operation  is  very  advan- 
tageous economically. 

31  BODROUX,  Compt.  rend.,  157,  1428  (1913). 

12  E.  FISCHER  and  SPEIER,  Berichte,  28,  3252  (1895). 


756  CATALYSIS  IN  ORGANIC  CHEMISTRY  272 

756.  Emil  Fischer  has  shown  that  this  process  can  be  applied  not 
only  to  the  aliphatic  acids  as  Berthelot  had  found,  and  to  benzoic 
acid,  but  also  to  a  large  number  of  types  of  acids  whether  aliphatic  or 
aromatic : 

Monobasic  acids  (naphthoic,  phenyl-acetic) ; 

Unsaturated  monobasic  acids  (crotonic,  cinnamic) ; 

Saturated  dibasic  acids  (succinic,  phthalic),  or  unsaturated  (fumaric) ; 

Hydroxy-acids  (glycolic,  phenyl-glycolic) ; 

Phenol-acids  (salicylic) ; 

Ketone-acids  (laevulinic) ; 

Polybasic  hydroxy-acids  (malic,  tartaric,  citric,  mucic). 

The  yields  obtained  are  usually  very  satisfactory;  we  quote  some 
of  the  results  obtained  by  heating  for  4  hours  a  mixture  of  1  part  of 
the  acid  with  3  to  4  parts  of  ethyl  alcohol. 

%  Catalyst  %  Ester 

a-Naphthoic  acid 2.2  HC1  74.8 

Phenyl-acetic 2.2  H2S04  87.0 

Cinnamic 0.7  HC1  78.8 

Cinnamic  . 7.5  H2S04  89.7 

Crotonic 7.5  H2S04  54.3 

Phenyl-glycolic 2.2  HC1  67.5 

Laevulinic 0.7  HC1  76.5 

Succinic 0.8  HC1  73.9 

Succinic 8.0  HaSC^  73.9 

Fumaric    . 0.8  HC1  68.2 

Tartaric 0.8  HC1  72.8 

Malic 0.8  HC1  70.5 

757.  To  obtain  slightly  soluble  esters,  Bodroux  adds  to  a  mixture 
of  an  organic  acid  and  alcohol  its  weight  of  pure  commercial  hydro- 
chloric acid  diluted  with  its  own  volume  of  water:    in  the  cold  the 
mixture  becomes  turbid  in  a  few  hours  and  finally  gives  60  to  90  %  of 
ester.     This  process  works  well  for  phenyl-acetic  acid  with  various 
saturated  alcohols  but  not  so  well  for  benzoic,  salicylic  and  cinnamic 
acids.™ 

The  yields  are  less  satisfactory,  hardly  more  than  50  %,  with  allyl 
alcohol  or  with  the  secondary  alcohols,  isopropyl  and  cyclohexyl.  They 
are  worse  still  with  dimethyl-ethyl-carbinol  as  well  as  with  glycerine  and 
mannite?* 

88  BODROUX,  Ccmpt.  rend.,  157,  939  (1913). 
34  BODROUX,  Compt.  rend.,  157,  1428  (1913). 


273  DEHYDRATION  759 

758.  Senderens  and  Aboulenc,  who  do  not  seem  to  have  known  of 
the  work  of  Berthelot  and  of  Emil  Fischer,  have  described  as  new  the 
method  of  direct  esterification  of  alcohols  in  presence  of  small  amounts 
of  sulphuric  acid.    The  results  which  they  give  are  a  verification  and 
extension  to  other  alcohols  of  a  part  of  the  results  of  Emil  Fischer. 
But  they  have  thought  that  they  were  able  to  make  an  essential  dis- 
tinction in  the  mechanism  of  the  reaction  between  the  aromatic  acids 
that  can  be  regarded  as  substitution  products  of  acetic  acid,  e.g. 
phenyl-acetic,  on  the  one  side  and  straight  aromatic  acids  in  which  the 
carboxyl  is  attached  to  the  nucleus,  e.g.  benzoic  and  toluic,  on  the  other. 

For  the  first  class,  they  consider  the  speed  of  the  esterification  and 
the  amount  of  ester  formed  as  independent  of  the  amount  of  the  sul- 
phuric acid,  while  for  benzoic  acid,  for  example,  these  increase  with 
the  amount  of  the  acid,  "which  consequently  does  not  act  simply  as  a 
catalyst." 

This  distinction  can  not  be  admitted.  A  solid  catalyst,  up  to  a 
certain  limit,  acts  in  proportion  to  its  active  surface.  Soluble  cata- 
lysts, such  as  diastases  or  acids  in  hydration  reactions,  or  sulphuric 
acid  in  this  case,  act  proportionally  to  their  mass,  at  least  if  this  is  not 
too  large  for  the  total  volume  of  liquid,  and  this  is  as  true  for  acetic 
as  for  benzoic.  The  results  quoted  above  from  Berthelot  for  the  for- 
mation of  ethyl  acetate  in  the  presence  of  hydrochloric  acid,  show 
that,  in  the  cold,  the  rapidity  of  the  esterification  is  approximately 
proportional  to  the  amount  of  the  catalyst. 

The  difference  between  the  aliphatic  acids  and  their  analogs  and 
benzoic  acid  is  that  the  velocity  of  the  esterification  of  the  former  by 
the  catalytic  acid  is  much  greater  than  for  benzoic.36  To  obtain  the 
same  yield  of  ester  from  benzoic  a  larger  amount  of  the  catalyst  would 
have  been  required. 

Oxalic  acid  is  esterified  regularly  like  succinic. 

Furthermore  the  practical  yields  are  much  better  with  the  higher 
alcohols  since  with  the  less  soluble  esters  the  losses  in  the  necessary 
washings  with  water  and  alkaline  carbonate  solutions  are  less  serious. 

759.  According  to  the  same  authors  the  sulphuric  acid  can  be  re- 
placed by  double  its  weight  of  anhydrous  aluminum  sulphate  or  potas- 
sium bisulphate.™ 

86  The  slowness  of  esterification  of  benzoic  acid  as  compared  with  acetic  acid  is 
shown  by  the  work  of  FREAS  and  REID,  [(J.  Amer.  Chem.  Soc.,  40, 569  (1918)],  who 
found  it  necessary  to  heat  benzoic  acid  with  methyl  and  ethyl  alcohols  to  200°  for 
96  hours  to  insure  reaching  the  limit  of  esterification  while  BERTHELOT  and  ST. 
GILLES  found  24  hours  sufficient  even  at  170°.  —  E.  E.  R. 

86  SENDERENS  and  ABOULENC,  Compt.  rend.,  152,  1671  and  1855  (1911)  and 
153,  881  (1911). 


760  CATALYSIS  IN  ORGANIC  CHEMISTRY  274 

760.  Glycerine  mixed  with  acetic  acid  (1  molecule  of  glycerine  to 
3  of  the  acid)  gives  on  boiling  under  reflux  for  1  hour,  esterification 
amounting  to  0.4  molecule  of  acid:   by  the  addition  of  5%  potassium 
bisulphate,  the  amount  esterified  reaches  1.2  molecules. 

With  2%  anhydrous  aluminum  sulphate  ......     1.5  mol. 

1  %  sulphuric  acid  .............     1.5  mol. 

By  starting  with  1  molecule  of  glycerine  and  12  acetic  acid,  the 
amount  esterified  by  boiling  1  hour  is  : 

With  the  aluminum  sulphate    .........     2  mol.  acid 

sulphuric  acid    .............     3  mol.  acid 

Triacetine  is  thus  reached  and  there  would  be  no  advantage  in 
increasing  the  amount  of  the  catalyst.37 

761.  Esterification  by  Acetanhydride.    A  common  method  of  pre- 
paring the  acetates  of  alcohols  or  of  poly-alcohols  is  to  heat  them  with 
acetanhydride. 

R.OH  +  (CH3.CO)20  =  2CH3.C02R  +  H2O.38 

By  this  means  all  the  hydroxyl  groups  of  a  complex  molecule  are 
esterified.  The  presence  of  a  certain  amount  of  sodium  acetate  favors 
the  action  of  the  anhydride. 

Still  better  results  are  obtained  by  adding  to  an  alcohol  four  times 
its  weight  of  acetanhydride  and  a  small  fragment  of  fused  zinc  chloride. 
The  reaction  becomes  very  rapid  immediately.  In  the  case  of  glyc- 
erine a  veritable  explosion  is  caused.  With  mannite,  however,  it  is 
regular  and  yields  in  a  few  minutes  mannite  hexa-acetate,  melting  at 


Catalytic  Esterification  in  Gaseous  System 

762.  The  assumption  of  an  unstable  combination  between  the 
dehydrating  oxides  and  the  alcohols  has  been  a  basis  for  the  prediction 
of  various  reactions  which  have  been  realized  by  experiment,  such  as 
the  formation  of  mercaptans  and  aliphatic  amines.  Sabatier  and 
Mailhe  thought  that  it  might  be  expected  that  these  combinations 

37  SENDERENS  and  ABOULENC,  Compt.  rend,,  158,  581  (1914). 

88  I  think  it  better  to  write  the  reaction  thus: 

R.  OH  +  (CH,.  CO)8O  -  CHjCOjR  +  CH8COjH. 

An  excess  of  the  anhydride  is  always  used  and  the  reaction  goes  to  completion 
since  no  water  is  formed  to  reverse  it.  —  E.  E.  R. 

89  FRANCHIMONT,  Berichte,  12,  2059  (1879). 


275  DEHYDRATION  764 

would  play  a  part  analogous  to  that  of  the  acid  sulphuric  esters,  that 
is,  that  the  dehydrating  oxides  would  act  as  esterification  catalysts.40 

763.  As  has  already  been  indicated,  if  a  mixture  of  the  vapors  of 
an  alcohol  and  an  organic  acid  be  passed  through  a  60  cm.  tube  heated 
between  300  and  360°,  the  proportion  of  ester  formed  during  the  pas- 
sage is  absolutely  negligible,   but  the  presence  of  a  catalytic  oxide 
changes  the  case  entirely.     Let  us  suppose  that  the  tube  contains  a 
catalytic  oxide,  MO,  derived  from  the  metallic  hydroxide,  M  (OH)2,  an 
amphoteric  hydroxide. 

The  reaction  can  take  three  different  courses: 

1st.  The  acid  may  combine  to  form  a  salt,  unstable  for  those  oxides 
which  catalyze  acids,  and  breaking  down  to  regenerate  the  oxide  and 
forming  a  symmetrical  ketone  (837): 

(1)  MO  +  2R.COOH  =  H20  +  (R.COO)2M  =  H20  +  MO  +  C02 
+  R.CO.R. 

ketone 

2nd.  The  oxide  may  combine  with  the  alcohol  to  form  an  unstable 
salt: 

MO  +  2CnH2n+1.OH  =  H20  +  M(OCnH2n+1)2. 

This  unstable  complex  can  decompose  in  two  ways,  either  by  itself 
to  give  the  unsaturated  hydrocarbon:41 

(2)  M(OCnH2n+1)2  =  MO  +  H20  +  2CnH2n 
or  with  the  aid  of  the  acid  to  form  an  ester: 

(3)  M(OCnH2n+1)2+2R.CO.OH=MO+H20+2R.CO.OCnH2n+1. 

In  any  case  the  catalytic  oxide  is  regenerated  and  can  continue  the 
same  effects.  Furthermore  in  reaction  (3),  the  water  produced  tends  to 
destroy  the  combination,  M  (OCnH2n+i)2,  and  consequently  limits  the  for- 
mation of  the  ester  which  results  from  it.  Since  these  reactions  are 
very  rapid,  the  esterification  limit  will  be  reached  quickly,  the  cata- 
lytic oxide  acting  like  the  platinum  sponge  in  the  combination  of 
iodine  and  hydrogen  (19). 

764.  We  may  have  simultaneously  formation  of  a  ketone,  produc- 
tion of  unsaturated  hydrocarbon   (or  ether),  and  the  rapid  reversible 
formation  of  the  ester;  this  is  what  is  observed  when  a  mixture  of  the 
vapors  of  ethyl  alcohol  and  acetic  acid  is  passed  over  thoria  or  alumina 
heated  to  about  400°. 

If  the  conditions  are  such  that  reactions  (1)  and  (2)  do  not  take 
place,  (3)  will  be  the  only  one  and  we  will  have  an  advantageous 
catalytic  formation  of  ester. 

40  SABATIER  and  MAILHE,  Compt.  rend.,  150,  823  (1910). 

41  In  the  case  of  methyl  alcohol,  this  decomposition  gives  methyl  ether. 


766  CATALYSIS  IN  ORGANIC  CHEMISTRY  276 

To  obtain  this  result  it  is  necessary  to  operate  at  such  low  temper- 
atures that  the  acids  are  not  decomposed  and  that  the  decomposition 
into  unsaturated  hydrocarbon  is  not  too  rapid. 

765.  Thoria,  which  is  the  most  active  catalyst  for  the  destruction 
of  adds  and  which,  likewise,  has  a  powerful  dehydrating  effect  on 
alcohols,  would  doubtless  be  less  advantageous  than  titania,  which  pro- 
duces these  effects  less  vigorously. 

766.  With  aromatic  acids,  such  as  benzoic  and  its  homologs  which 
have  the  carboxyl  attached  to  the  nucleus,  thoria  does  not  produce 
any  appreciable  decomposition  even  up  to  450° :   it  can  be  predicted 
that  reaction  (1)  will  not  take  place.    Experiment  has  shown  that  this 
is  the  case  and  that  at  350°  reaction   (2)  is  negligible  as  compared 
with  reaction  (3),  which  goes  very  rapidly.    By  vaporizing  a  saturated 
solution  of  benzoic  acid  in  an  alcohol  (there  are  at  least  12  molecules 
of  the  alcohol  to  1  of  the  acid)  and  passing  the  vapors  over  a  train  of 
thoria  at  350°,  there  is  no  appreciable  formation  of  the  unsaturated 
hydrocarbon,  but  the  benzoic  acid  is  almost  totally  esterified.    Methyl, 
ethyl,  propyl,  butyl,  isobutyl,  isoamyl  and   allyl  benzoates  have  been 
obtained  advantageously  in  this  way. 

In  spite  of  their  greater  tendency  to  form  unsaturated  hydro- 
carbons, the  secondary  alcohols  can  form  benzoic  esters  with  fairly 
good  yields  :  this  is  the  case  with  isopropyl  alcohol  with  which  the 
formation  of  propylene  is  of  minor  importance.  Cyclohexyl  alcohol 
is  more  delicate,  but  nevertheless  gives  a  fairly  good  yield  of  the 
benzoate. 

Analogous  results  are  obtained  with  the  three  toluic  acids  which 
are  readily  esterified  by  thoria  at  350-380°,  but  the  practical  prepara- 
tion of  these  esters  is  less  advantageous  on  account  of  the  smaller 
solubility  of  these  acids,  particularly  the  para,  in  the  alcohols:  the 
meta  is  the  most  soluble.42 

767.  Titania  enables  us  to  esterify  various  acids  in  the  same  man- 
ner.   If  a  mixture  of  equivalent  amounts  of  the  vapors  of  a  primary 
alcohol  and  an  aliphatic  acid,  other  than  formic,  is  passed  over  a  train 
of  this  oxide  maintained  at  280-300°,  rapid  esterification  takes  place, 
reaching  a  limit  slightly  above  that  observed  by  Berthelot  and  Men- 
schutkm  in  their  experiments  on  direct  esterification.    The  production 
of  gas  on  account  of  the  destruction  of  the  acid  or  the  alcohol  is  abso- 
lutely negligible. 

768.  It  is  known  that  the  presence  of  a  catalyst  does  not  change 
the  location  of  the  limit  in  reversible  reactions,  but  diminishes  greatly 
the  time  required  to  reach  that  limit.    In  this  particular  case,  Berthe- 

42  SABATIEB  and  MAILHE,  Compt.  rend.,  152,  358  (1911). 


277  DEHYDRATION  770 

lot  found  that  the  limit  is  moved  somewhat  by  elevation  of  the  tem- 
perature. For  equivalent  amounts  of  ethyl  alcohol  and  acetic  acid,  he 
found  the  following  values  of  the  limit: 

In  the  cold  (10  years) 65.2  % 

At  100°  (200  hours) 65.6 

170°  (42  hours) 66.5 

200°  (24  hours) 67.3 

The  figures  show  that  the  limit  is  not  fixed  but  progresses  slowly 
with  the  temperature  and  suggest  a  still  higher  value  for  the  limit  at 
280-300°. 

769.  At  155°,  Menschutkin  found  for  various  alcohols  mixed  with 
equivalent  amounts  of  different  acids,  the  following  limits : 4S 

Acetic  acid  +  methyl  alcohol 69.6  % 

Acetic  acid  +  ethyl  alcohol 66.6 

Acetic  acid  +  propyl  alcohol 66.9 

Acetic  acid  -f  butyl  alcohol 67.3 

Acetic  acid  +  isobutyl  alcohol 67.4 

Propionic  acid  +  isobutyl  alcohol     ....  68.7 

Butyric  acid  -f  isobutyl  alcohol     ....  69.5 

Isobutyric  acid  +  isobutyl  alcohol     ....  69.5 

Sabatier  and  Mailhe  obtained  the  following  limits  with  titania  at 
280-300°: 

Acetic  acid  +  isobutyl  alcohol     ....  69.5  % 

Propionic  acid  +  methyl  alcohol 72.9 

Propionic  acid  +  isoamyl  alcohol 72 

Butyric  acid  +  ethyl  alcohol 71 

Butyric  acid  +  isoamyl  alcohol 72.7 

Isobutyric  acid  +  ethyl  alcohol 71 

These  values  are  slightly  higher  than  the  corresponding  figures 
obtained  at  lower  temperatures. 

770.  Furthermore,  in  this  rapid  catalytic  esterification,  the  same 
laws  are  found  to  hold  as  Berthelot  formulated  for  direct  esterification. 
An  excess  of  one  constituent  increases  the  amount  of  the  other  com- 
bined.   Thus  for  1  molecule  of  isobutyric  acid  with  1,  2,  and  4  mole- 
cules of  ethyl  alcohol,  the  following  percentages  of  the  acid  were 
esterified: 

With  1  molecule .     71.0% 

2  molecules     83.5 

4  molecules     .   .   ,   ..........     91.0 

48  MENSCHUTKIN,  Ann.  Chim.  Phys.  (5),  20,  289,  and  23,  64  (1880). 


771  CATALYSIS  IN  ORGANIC  CHEMISTRY  278 

In  the  presence  of  more  than  10  molecules  of  alcohol  the  esteri- 
fication  of  the  acid  is  nearly  complete  and,  conversely,  almost  all  of 
the  alcohol  is  esterified  by  a  large  excess  of  the  acid.  The  relative 
cost  of  the  alcohol  and  acid  in  such  cases  decides  which  conditions  are 
most  economical. 

771.  Sabatier  and  Mailhe  have  prepared  easily  the  methyl,  ethyl, 
propyl,  butyl,  isobutyl  and  isoamyl  esters  of  acetic,  propionic,  butyric, 
isobutyric,  isovaleric,  caproic,  pelargonic  and  crotonic,  etc.,  acids. 

Benzyl  alcohol  gives  equally  good  results  with  various  acids.  The 
dehydration  to  the  resinous  hydrocarbon,  (C7H6)X,  which  is  effected 
so  rapidly  by  catalytic  oxides,  hardly  takes  place  at  all  in  the  presence 
of  acid  vapors.44 

772.  Sabatier  and  Mailhe  have  found  further  that  it  is  not  indis- 
pensable to  use  as  high  a  temperature  as  280°,  which  is  usually  the 
most  advantageous. 

The  catalytic  activity  continues,  though  it  falls  off  gradually,  to 
temperatures  much  lower  where  the  acids  and  alcohols  are  stable.  In 
this  titania  is  superior  to  thoria.45  By  operating  with  equal  molecules 
of  ethyl  alcohol  and  acetic  acid  and  passing  the  vapors  over  a  50  cm. 
train  of  the  oxide  at  the  rate  of  0.2  molecule,  or  21  g.,  per  hour,  Sa- 
batier and  Mailhe  obtained  the  following  percentages  of  esterification : 

With  thoria  With  titania 

At  150° 11%          ...     20% 

170° 26  .    .    .     — 

230° 45  ...     60 

Besides,  the  catalytic  power  of  titania  persists  almost  indefinitely; 
it  was  not  diminished  by  experiments  on  varied  mixtures  of  alcohols 
and  acids  extending  over  20  days. 

773.  Formic  acid  can  be  esterified  at  these  temperatures  at  which 
it  is  fairly  stable.  By  operating  with  equal  molecules  of  formic  acid  and 
ethyl  alcohol,  distributed  by  the  same  capillary  tube  through  which 
the  molecular  volume  passed  very  rapidly,  in  spite  of  this  unfavorable 
circumstance,  the  following  amounts  were  esterified  over  titania: 

At  120° 47  % 

150° 65% 

The  esterification  limit  is  nearly  reached  even  at  150°  at  which 
the  decomposition  of  formic  acid  into  gaseous  products  is  still  incon- 
siderable. 

44  SABATIER  and  MAILHE,  Compt.  rend.,  152,  494  (1911). 

45  MAILHE  and  DE  GODON  [(Bull.  Soc.  Chim.,  29,  101  (1921)]  conclude  that 
ZrO2  is  as  good  as  or  better  than  TiOj.     MILLIGAN  and  REID  (unpublished  work) 
find  silica  gel  to  be  a  better  esterification  catalyst  than  either.  —  E.  E.  R. 


279  DEHYDRATION  778 

In  practice  formic  acid,  mixed  with  an  excess  of  the  desired  alcohol, 
is  passed  over  thoria  at  150°.  Methyl,  ethyl,  propyl,  butyl,  isoamyl  and 
benzyl  for  mates  have  been  readily  prepared  in  this  way. 

774.  The  comparison  of  these  results  has  led  Sabatier  and  Mailhe 
to  conclude  that  the  rapidity  of  the  esterification  of  the  primary  alco- 
hols by  the  aliphatic  acids,  in  presence  of  catalysts,  is  directly  propor- 
tional to  the  kinetic  velocities  of  the  reacting  molecules;  it  is  as  much 
greater  as  the  molecules  are  lighter  and  it  can  be  inferred  that  the  reason 
is  to  be  found  in  the  greater  rapidity  of  gaseous  interchanges  on  the 
catalyst. 

775.  The  secondary  alcohol,  isopropyl,  mixed  with  isobutyric  acid 
does  not  give  any  evolution  of  propylene  with  titania  below  300°. 
The  proportion  esterified  was: 

At  235° 16.5% 

256° 21 

292° 37 

For  primary  propyl  alcohol,  the  amount  is  50%  at  235°  and  72% 
at  292°. 

776.  Trimethyl-carbinol    (tertiary  butyl   alcohol)   likewise  mixed 
with  isobutyric  acid,  gives  6  %  ester  at  235°  with  no  formation  of  the 
hydrocarbon.    With  the  isomeric  primary  alcohol,  isobutyl,  it  is  22  %. 
It  is  only  at  255°  that  the  decomposition  into  butylene  begins  to 
manifest  itself.     At  265°  it  is  quite  rapid  and  the  acidity  of  the  mix- 
ture increases  on  account  of  the  destruction  of  the  alcohol  in  place  of 
diminishing  by  esterification. 

777.  These  results  agree  well  with  the  weakening  of  the  alcoholic 
function  in  secondary  and  particularly  in  tertiary  alcohols.     The  ve- 
locity of  the  catalytic  esterification  should  be  at  the  same  time  a 
function  of  the  speed  of  the  gaseous  interchanges,  in  consequence  of 
the  smallness  of  the  molecules  and  also  of  the  facility  with  which  the 
alcohol  forms  the  temporary  unstable  complexes  with  the  catalytic 
oxide.46 

778.  Beryllium  oxide  also  can  be  employed  as  an  esterification 
catalyst.    With  this  oxide  heated  to  310°,  yields  of  above  70  %  of  ester 
can  be  obtained.    The  catalyst  can  be  regenerated  by  calcining  at  a 
red  heat.     With  this  catalyst  esters  of  tertiary  alcohols  and  of  high 
molecular  weight  acids  can  be  prepared.47  48 

48  SABATIER  and  MAILHE,  Compt.  rend.,  152,  1044  (1911). 

47  HAUSER  and  KLOTZ,  Chem.  Zeit.,  37,  146  (1913). 

48  I  have  tried  to  prepare  esters  by  the  use  of  beryllia  and  so  has  Dr.  MILLIQAN 
but  neither  of  us  has  been  able  to  verify  the  statements  of  HAUSER  and  KLOTZ. 
—  E.  E.  R. 


779  CATALYSIS  IN  ORGANIC  CHEMISTRY  280 

§  6.  — ELIMINATION  OF  WATER  BETWEEN  ALCOHOLS 
AND  ALDEHYDES  OR  KETONES 

779.  The  elimination  of  water  between  alcohols  and  aldehydes  or 
ketones  can  take  place  in  several  ways.    The  one  way  is  to  a  certain 
extent  comparable  to  esterification  and  leads  to  acetals;  it  can  hardly 
be  realized  except  in  liquid  systems.     The  other,  more  exceptional, 
gives  rise  to  hydrocarbons  and  is  effected  in  gaseous  systems. 

I.  —  Formation  of  Acetals 

780.  Aldehydes  can  combine  directly  with  alcohols  to  give  acetals : 

R.CHO  +  2R'OH  =  H20  +  R.CH(OR/)2. 

aldehyde  alcohol  acetal 

But  the  direct  formation  is  very  imperfect,  unless  suitable  catalysts 
are  used. 

Good  yields  are  obtained  by  passing  for  a  long  time  a  current  of 
pure  phosphine  through  a  well  cooled  mixture  of  the  aldehyde  and 
alcohol:  by  this  means  acetaldehyde  has  been  made  to  combine  with 
ethyl,  propyl  and  isobutyl  alcohols.49 

The  combination  of  alcohols  and  aldehydes  is  greatly  aided  by  the 
presence  of  a  certain  amount  of  glacial  acetic  add.60 

781.  Trioxymethylene,  the  condensation  product  of  formaldehyde, 
readily  forms  methylal,  HCH(OCH3)2,  when  it  is  mixed  with  methyl 
alcohol  and  heated  on  the  water  bath  for  10  hours  with  3  %  of  ferric 
chloride. 

782.  A  good  method  for  preparing  acetals  is  to  mix  the  aldehyde 
with  the  proper  amount  of  alcohol  containing  1  %  of  hydrogen  chloride 
(the  gas  dissolved)  and  digest  the  mixture  for  18  to  20  hours :   the 
yields  are  usually  satisfactory.51 

To  obtain  acetals  from  acetaldehyde  with  various  aliphatic  alco- 
hols, 40  g.  of  acetaldehyde  is  mixed  with  60  g.  of  the  alcohol  and  1  cc. 
concentrated  hydrochloric  add  is  added  and  this  mixture  digested  24 
hours  with  a  saturated  solution  of  sodium  chloride  and  10  g.  of  the 
solid  salt.52 

783.  The   action   of  ethyl  ortho-formate  on  aldehydes  or  ketones 
readily  produces  their  combinations  with  ethyl  alcohol;   but  this  re- 

49  ENGEL  and  GIRARD,  Jahresb.,  1880,  694. 

60  GBUTHER,  Annalen,  126,  62  (1863). 

61  E.  FISCHER  and  GIEBE,  Berichte,  30,  3053  (1897). 

82  KING  and  MASON,  English  patent,  101,428  of  1916,  J.  Soc.  Chem.  Ind.,  35, 
1131  (1916). 


281  DEHYDRATION  784 

action  does  not  take  place  without  the  aid  of  suitable  catalysts.  These 
may  be  quite  varied,  e.g.  strong  mineral  acids,  ferric  chloride,  ammo- 
nium chloride,  ethyl-,  diethyl-,  or  triethyl-amine  hydrochlorides,  potassium 
bisulphate,  ammonium  sulphate  or  nitrate.  Boiling  for  a  few  minutes 
is  sufficient  to  assure  the  formation. 

Thus  to  prepare  the  acetal  from  ethyl  alcohol  and  benzaldehyde,  1 
molecule  of  the  aldehyde  is  mixed  with  0.1  molecule  ethyl  ortho-form- 
ate and  poured  into  3  molecules  of  the  alcohol  and  a  little  dry  hy- 
drogen chloride  is  passed  in.  After  ten  minutes  boiling,  the  acetal, 
C6H5.CH(OC2H5)2  is  obtained  in  99%  yield.  By  using  2  g.  ammo- 
nium chloride,  the  yield  is  97  %. 

The  diethyl  acetal  of  acetone  is  obtained  thus  with  66%  yield. 

If  the  boiling  is  prolonged  too  greatly,  the  yield  is  more  and  more 
diminished,  which  shows  that  the  catalyst  tends  to  destroy  by  hydrol- 
ysis the  acetal  which  it  has  formed.63 

n.  —  Formation  of  Hydrocarbons  in  Gaseous  System 

784.  The  dehydrating  action  of  oxides  such  as  alumina  on  a  mix- 
ture of  an  alcohol  and  an  aldehyde  can  eliminate  all  of  the  oxygen  as 
water  producing  a  doubly  unsaturated  hydrocarbon. 

This  takes  place  when  a  mixture  of  ethyl  alcohol  and  acetaldehyde 
is  passed  over  the  impure  alumina  formed  by  calcining  ammonium 
alum.  Butadiene,  boiling  at  2°,  is  obtained: 

CH2OH.CH3  +  OCH.CH3  =  2H20  +  CH2 :  CH.CH  :  CH2. 

With  pure  alumina,  methyl-allene,  CH3 .  CH :  C  :  CH2,  is  also 
formed.  This  reaction  can  be  applied  to  the  synthesis  of  rubber  by 
the  polymerization  of  the  hydrocarbon  obtained  (213).  From  100  g. 
of  the  mixture  of  aldehyde  and  alcohol,  25  g.  of  the  crude  hydrocarbon 
may  be  obtained  or  16  to  18  g.  of  pure  butadiene  which  may  be  totally 
transformed  into  rubber.54 

Similarly  acetaldehyde,  with  isopropyl  or  propyl  alcohols,  leads  to 
piperylene,  CH3 .  CH  :  CH .  CH  :  CH2,  boiling  at  42°.64 

»  CLAISEN,  Berichte,  40,  3903  (1907). 

64  OSTROMUISSLENSKII  and  KELBASINSKI,  J.  Russian  Phys.  Chem.  Soc.,  47, 1509 
(1915);  C.  A.,  10,   3179  (1916). 


CHAPTER  XVII 
DEHYDRATION  (Continued) 
§  7.  —  DEHYDRATION  OF  PHENOLS  ALONE 

785.  One  method  of  preparing  ethers  from  phenols  is  to  distil  dry 
aluminum  phenylates:  this  works  well  for  phenyl  ether  and  for  the 
ethers  of  ortho  and  para  cresols.1  This  method  of  preparation  leads 
us  to  foresee  that  phenyl  ethers  can  be  prepared  catalytically  by  the 
action  of  a  catalytic  oxide  such  as  thoria  on  the  vapors  of  the  phenol 
at  a  suitable  temperature,  the  mechanism  of  dehydration  depending, 
as  with  the  alcohols,  on  the  formation  of  an  unstable  thorinate  which 
decomposes  regenerating  thoria. 

We  have  :         20^  .  OH  +  Th02  =  H2O  +  Th(OC6H5)2 


thorinate 

and  then:  Th(OC6H5)2  =  ThO2  +  (CeH^O. 

ether 

This  prediction  having  been  verified,  Sabatier  and  Mailhe  have 
based  on  it  an  advantageous  method  for  the  preparation  of  phenol  ethers 
by  the  use  of  thoria.2 

786.  Simple  Phenol  Ethers.    The  vapors  of  the  phenol  are  passed 
over  a  train  of  thoria  kept  at  400-500°.    If  the  phenol  is  a  liquid,  it 
is  introduced  directly  by  means  of  the  capillary  tube  (181)  ;    if  it  is  a 
solid,  its  benzene  solution  is  used.    The  reaction  products  are  shaken 
with  caustic  soda,  which  extracts  the  unchanged  phenol  leaving  the 
ether  which  is  obtained  entirely  pure  by  one  distillation.    Phenyl  ether 
can  be  prepared  in  this  way  very  economically  and  in  great  purity 
with  a  yield  of  50%  or  better;   meta  and  para  cresyl  ethers  can  be 
readily  obtained,  while  ethers  are  more  difficult  to  obtain  from  ortho 
cresol  and  from  xylenol(l,34}?  and   poor    results   are   gotten   with 
carvacrol.4 

787.  Diphenylene  Oxides.    This  method  leads  to  the  simultaneous 
formation  of  diphenylene  oxides,  fluorescent  compounds,  less  volatile 
than  the  ethers,  and  formed  by  the  loss  of  H2. 

With  ordinary  phenol  at  475°,  there  is  formed  along  with  phenyl 

1  GLADSTONE  and  TRIBE,  J.  Chem.  Soc.,  41,  9  (1882),  and  49,  25  (1886). 

2  SABATIER  and  MAILHE,  Compt.  rend.,  151,  492  (1910). 

s  SABATIER  and  MAILHE,  Bull  Soc.  Chim.  (4),  n,   843  (1912). 
*  SABATIER  and  MAILHE,  Compt.  rend.,  158,  608  (1914). 

282 


283  DEHYDRATION  789 

ether,  boiling  at  253°  and  melting  at  28°,  a  considerable  amount  of 

C6H4\ 
diphenylene  oxide,  |  0,  boiling  at  287°  and  melting  at  85°,  which 

C6H4/ 

had  previously  been  obtained  by  distilling  calcium  phenylate.5  The 
cresols,  xylenols,  and  naphthols  give  rise  to  the  formation  of  similar 
products.6 

788.  Mixed  Phenol  Ethers.     By  dehydrating  over  thoria,  not  a 
single  phenol,  but  a  mixture  of  two  phenols,  the  product  contains 
along  with  the  simple  ethers  of  the  two  phenols  and  the  diphenylene 
oxides,  an  amount,  usually*  considerable,  of  the  mixed  ether  derived 
from  the  two  phenols  which  can  be  separated  by  careful  fractionation. 
Sabatier  and  Mailhe  have  prepared  the  following  mixed  ethers,  phenyl- 
o.cresyl,  phenyl-m.cresyl,  phenyl-p.cresyl,  phenyl-a-naphthyl,  phenyl-ft- 
naphthyl,  phenyl-carvacryl,  p.cresyl-carvacryl,  as  well  as  the  phenylene- 
naphthylene  oxides.7 

§  8.  —  ELIMINATION  OF  WATER  BETWEEN  PHENOLS 
AND  ALCOHOLS 

Synthesis  of  Alkyl  Phenol  Ethers 

789.  Sabatier  and  Mailhe  have  shown  that  catalytic  oxides  such 
as  thoria  readily  eliminate  water  from  a  phenol  and  an  alcohol  with 
the  formation  of  a  mixed  ether.8    This  is  a  very  advantageous  method 
of  preparing  mixed  ethers.     All  that  is  necessary  is  to  pass  a  mixture 
of  the  phenol  with  an  excess  of  the  alcohol  over  thoria  at  390-420.° 
With  methyl  alcohol,  which  is  dehydrated  by  thoria  very  slowly,  the 
results  are  particularly  good.    The  excess  of  the  alcohol  and  most  of 
the  unchanged  phenol  are  separated  from  the  ether  by  fractionation. 
The  remainder  of  the  phenol  is  extracted  by  caustic  soda  from  the 
mixed  ether,  which  is  purified  by  a  single  distillation. 

In  this  way,  Sabatier  and  Mailhe  have  prepared  the  methyl  ethers 
of  phenol,  the  three  cresols,  xylenol(l,3,4),  thymol,  carvacrol,  and  a- 
and  ft-naphthols. 

At  the  same  time  small  quantities,  more  or  less  important  accord- 
ing to  the  phenol,  of  the  phenol  ether  and  diphenylene  oxide  are  ob- 
tained. A  mixture  of  methyl  alcohol  and  carvacrol  gives  methyl- 
carvacryl  ether,  along  with  di-carvacryl  ether  and  carvacrylene.9 

5  NiEDERHXusERN,  Berichte,  15,  1120  (1882). 

6  SABATIER  and  MAILHE,  Compt.  rend.,  151,  494  (1910). 

7  SABATIER  and  MAILHE,  Compt.  rend.,  155,  260  (1912),  and  158,  608  (1914). 

8  SABATIER  and  MAILHE,  Compt.  rend.,  151,  359  (1910). 

9  SABATIER  and  MAILHE,  Compt.  rend.,  158,  608  (1914). 


790  CATALYSIS  IN  ORGANIC  CHEMISTRY  284 

The  other  alcohols,  in  spite  of  their  own  rapid  decomposition  by 
thoria,  can  readily  give  the  mixed  ethers  :  one  operates  around  420° 
on  phenol  dissolved  in  excess  of  the  alcohol,  a  part  of  which  is  decom- 
posed forming  the  unsaturated  hydrocarbon.  Ethyl-,  propyl-,  and 
isoamyl-phenyl  ethers  have  been  prepared  in  this  way. 

§  9.  — ELIMINATION  OF  WATER  BETWEEN  A  PHENOL 
AND  AN  AMINE 

790.  Nothing  worth  while  is  accomplished  by  passing  a  phenol  and 
ammonia  over  a  catalytic  oxide  at  400°.    The  production  of  amines  is 
quite  negligible. 

We  may  mention  as  a  catalytic  reaction  of  this  sort,  the  action  of 
a-  and  (3-naphthols,  on  aniline,  the  toluidines  and  other  aromatic 
amines,  when  they  are  heated  7  hours  to  about  200°  in  the  presence  of 
1  %  of  iodine.  The  corresponding  secondary  amines  are  obtained  with 
satisfactory  yields.10 

§  io.  — ELIMINATION  OF  WATER  BETWEEN  PHENOLS 
AND  HYDROGEN  SULPHIDE 

791.  Sabatier  and  Mailhe  have  found  that  by  passing  the  vapors 
of  a  phenol  and  hydrogen  sulphide  over  thoria  between  430  and  480°, 
the  corresponding  thiophenol  is  obtained. 

C6R5.OH  +  H2S  =  H20  +  C6R5.SH. 

But  the  yield  is  not  so  good  as  with  alcohols  (744),  and  is  not 
above  10%  in  the  most  favorable  case.  A  temperature  of  500°  de- 
creases the  yield  on  account  of  the  serious  decomposition  of  the  hy- 
drogen sulphide.  Hence  the  reaction  is  of  no  practical  use  but  is  of 
only  scientific  interest.11 

The  yields  are  still  less  when  other  oxides  are  used.  With  phenol, 
the  following  yields  were  obtained  at  450°  :12 

Alumina 0.4% 

Zirconia 1.5 

Blue  oxide  of  molybdenum 1.8 

Blue  oxide  of  tungsten      1.5 

Chromic  oxide 2.5 

Uranous  oxide 3.8 

Thoria  .   ,   ,,.    ...,!;;...    ...    ...    .  8.0 

10  KNOEVENAGEL,  J.  prakt.  Chem.  (2),  89,  16  (1914). 

11  SABATIER  and  MAILHE,  Compt.  rend.,  150,  1220  (1910). 

12  SABATIER  and  MAILHE,  Compt.  rend.,  150,  1570  (1910). 


285  DEHYDRATION  794 

§  ii.  —  ELIMINATION  OF  WATER  BETWEEN  PHENOLS 
AND  ALDEHYDES 

792.  For  some  years  there  has  been  prepared  under  the  name  of 
bakelite,  a  resinous  material  very  resistant  to  shock  and  to  pressure 
and  endowed  with  insulating  properties  of  the  first  order.  It  results 
from  the  condensation  of  phenol  or  cresols  with  formaldehyde  in  the 
presence  of  various  catalysts,  chiefly  substances  with  alkaline  re- 
action.13 According  to  Baekeland,14  who  has  given  his  name  to  the 
product,  one  of  the  materials,  called  bakelite  C,  results  from  the  re- 
action of  7  molecules  of  formaldehyde  with  6  of  phenol: 


6C6H5OH  +  7CH20  =  C43H3807  +  6H2O. 

The  formaldehyde  can  be  replaced  by  methylal,  trioxymethylene,  or 
hexamethylene-tetramine. 

The  products  obtained  are  very  variable  according  to  the  operating 
conditions  and  either  liquid  intermediate  substances  or  solids  corre- 
sponding to  an  advanced  stage  of  molecular  condensation  may  be  ob- 
tained. The  condensation  to  the  solid  products  can  be  effected  by 
acid  catalysts  such  as  hydrochloric  acid. 


§  12.  —  FORMATION  OF  PHENOLIC  GLUCOSIDES 

793.  Quinoline  employed  in  small  proportion  causes  phenols  to 
react  with  acetyl-brom-glucose  forming  the  acetylate  of  the  corre- 
sponding phenyl-glucoside.  By  warming  for  1  hour  50  g.  acetyl-brom- 
glucose  with  160  g.  phenol  in  the  presence  of  19  g.  quinoline,  the 
tetra-acetyl-phenyl-glucoside  is  obtained,  the  hydrolysis  of  which  by 
baryta  water  separates  the  phenyl-glucoside.15 


§  13.—  DEHYDRATION  OF  ALDEHYDES  OR  OF  KETONES 

794.  Frequently  the  presence  of  certain  substances  causes  the 
condensation  of  two  or  more  molecules  of  aldehydes  or  of  ketones 
with  the  elimination  of  water  and  the  formation  of  a  single  molecule 
retaining  only  one  aldehyde  or  ketone  group  and  containing  double 
bonds.16 

13  LEBACH,  J.  Soc.  Chem.  Ind.,  32,  559  (1913).  —  Caoutchouc  and  Gutta-percha, 
14,  9339  (1917).    HUTIN,  Ibid.,  16,  9987  (1919). 

14  BAEKELAND,  J.  Ind.  Eng.  Chem.,  i,  149  (1909). 

16  E.  FISCHER  and  VON  MECHEL,  Berichte,  49,  2813  (1916). 
11  SABATIER  and  MAILHE,  Compt.  rend.,  150,  1220  (1910). 


795  CATALYSIS  IN  ORGANIC  CHEMISTRY  286 

This  process  is  called  crotonization  from  croton  aldehyde  which  is 
formed  from  acetaldehyde:17 

CH3 .  CHO  +  CH3 .  CHO  =  H2O  +  CH3 .  CH  :  CH .  CHO. 

Reactions  of  this  kind  can  take  place  between  molecules  of  dif- 
ferent aldehydes  or  ketones. 

Crotonization  in  Liquid  Medium 

795.  The  catalysts  that  are  able  to  cause  the  crotonization  of  al- 
dehydes and  ketones  in  liquid  medium  are  quite  varied  and  their 
action  is  generally  quite  slow  :    soda,  potash,  hydrochloric  acid,  zinc 
chloride,  lime,  aluminum  chloride  and  sodium  acetate  may  be  mentioned. 

In  order  to  transform  acetaldehyde  into  croton  aldehyde,  it  is 
heated  to  97°  for  36  hours  with  20  %  of  its  weight  of  a  water  solution 
of  sodium  acetate,1*  or  better  to  100°  for  48  hours  with  a  solution  of 
zinc  chloride.19 

Paraldehyde  in  contact  with  sulphuric  acid  also  gives  croton  al- 
dehyde.20 

The  same  process  applies  to  the  crotonization  of  propionic  aldehyde 
which  can  be  crotonized  by  heating  with  a  solution  of  caustic  soda.21 
The  same  agent  is  employed  for  butyric  aldehyde.22  Dry  hydrogen 
chloride23  or  a  solution  of  sodium  acetate  may  be  used  to  crotonize 
isobutyric  aldehyde?* 

Zinc  chloride,  or  alcoholic  potash,  causes  two  or  four  molecules  of 
heptaldehyde  to  condense.25  Contact  with  zinc  turnings  is  sufficient 
to  crotonize  isovaleric  aldehyde:  sodium,  caustic  potash  and  hydro- 
chloric acid  produce  the  same  effect.26 

796.  Croton  aldehyde  itself  mixed  with  acetaldehyde  and  zinc  chlo- 
ride at  100°,  undergoes  a  second  like  reaction  and  forms  hexadienal 
(boiling  at  about  172°)  ,27 

CH3.CH  :  CH.CHO  +  CH3.CHO  = 

H20  +  CH3.CH  :  CH.CH  :  CH.CHO. 

17  SABATIER  and  MAILHE,  Compt.  rend.,  150,  1570  (1910). 

18  LIEBEN,  Monatsh.,  13,  519  (1892). 

19  MULLER,  Bull.  Soc.  Chim.  (3),  6,  796  (1891). 

20  DELEPINE,  Ann.  Chim.  Phys.  (8),  16,  136  (1909),  and  20,  389  (1910). 

21  HOPPE,  Monatsh.,  9,  637  (1888). 

22  RAUPENSTRAUCH,  Monatsh.,  8,  112  (1887). 

21  (EcoNOMiDES,  Bull.  Soc.  Chim.  (2),  36,  209  (1881). 
24  FOSSEK,  Monatsh.,  2,  616  (1881). 
26  PERKIN,  Berichte,  15,  2804  (1882). 

26  RIBAN,  Bull.  Soc.  Chim.   (2),   18,   64   (1872).  —  KEKULE,  Berichte,  3,   135 
(1870).  — BORODIN,  Berichte,  6,  983  (1873). 

27  KEKULE,  Annalen,  162,  105  (1872). 


287  DEHYDRATION  799 

797.   Ordinary  acetone™  kept  for  a  long  time   in   contact  with 
lime,29  or   aluminum   chloride  30   is   transformed   into   mesityl   oxide: 

(CH3)2:CH.CO.CH3 
and  then  into  phorone: 

(CH3)2C  :  CH  .  CO  .  CH  :  C  (CH3)2. 

Cyclohexanone,  in  contact  with  sodium  ethylate  or  hydrochloric 
acid,    condenses   to   an   oily   compound   similar   to   mesityl   oxide,31 


CH 


/CH2.CO\  /CH2.CH2v 

C  :  C  CH2. 


798.  Crotonization  can  take  place  in  a  similar  manner  between 
different  molecules,  principally  between  a  molecule  of  acetone  and  one 
or  two  molecules  of  aldehyde.     The  presence  of  aqueous  or  alcoholic 
soda  is  most  frequently  efficient  in  causing  these  condensations  with 
the  elimination  of  one  or  two  molecules  of  water  giving  compounds 
containing  a  ketone  group  and  one  or  two  double  bonds. 

Benzaldehyde  gives  such  products  readily.  Thus  with  acetone  in 
prolonged  contact  with  aqueous  soda,  it  forms  successively  benzal- 
acetone  and  dibenzal-acetone  :  M 

C6H5.CHO  +  H2CH.CO.CH3  =  H2O  +  C6H5.CH  :  CH.CO.CH, 

and 

2C6HB.CHO  +  CH3.CO.CH3  =  2H2O  +  (C6H5.CH  :  CH)2CO. 

In  the  presence  of  a  little  soda  solution,  o.nitrobenzaldehyde  con- 
denses with  acetone  to  give  o.nitrobenzal-acetone:™ 

02N.C6H4.CHO  +  CH3.CO.CH3  = 

H2O  +  02N  .  C6H4  .  CH  :  CH  .  CO  .  CH3. 

799.  Benzaldehyde  condenses  with  acetophenone  in  the  presence  of 
hydrogen  chloride,34  or  of  a  few  cubic  centimeters  of  soch'um  meth- 
ylate,35  to  give  diphenyl-propenone,   C6H5  .  CH  :  CH  .  CO  .  C6H5. 

28  Pure  acetone  passed  over  heated  freshly  prepared  alumina  forms  condensa- 
tion products,  only  about  60%  of  the  acetone  passing  through  unchanged.     No 
gaseous  products  are  formed.  —  HOMER  ADKINS. 

29  FITTIG)  Annaltn,  no,  32  (1859). 

80  LOUISE,  Compt.  rend.,  95,  602  (1882). 

31  WALLACE,  Berichte,  29,  2955  (1896),  C.,  1897  (1),  322. 

82  CLAISEN  and  PONDER,  Annalen,  223,  139  (1884). 

33  BAEYER  and  DREWSEN,  Berichte,  15,  2856  (1882). 

34  CLAISEN  and  CLAPAREDE,  Berichte,  14,  2463  (1881). 
36  CLAISEN,  Berichte,  20,  657  (1887). 


800  CATALYSIS  IN  ORGANIC  CHEMISTRY  288 

The  same  aldehyde  gives  benzylidene-hydrindone  with  hydrindone 
and  a  little  alcoholic  potash: 


2y 

C6H  )CH2  +  OCH  .  C6H6  -»  C6H  )C  :  CH  .  C6H5.36 

\CO  /  \CO  / 

Cinnamic  aldehyde,  digested  several  hours  with  acetophenone  in 
contact  with  soda,  passes  into  diphenyl-pentadieneone:® 

C6H6  .  CH  :  CH  .  CH  :  CH  .  CO  .  C6H5. 

Cyclopentanone  condenses  with  two  molecules  of  benzaldehyde  in 
contact  with  soda.38 

800.  Citral  (50  cc.)  and  acetone  (65  cc.)  shaken  several  hours  with 
1  1.  of  4%  baryta  water  condense  to  pseudo-ionone™ 

Condensations  in  Gaseous  Phase 

801.  Catalytic  dehydrating  oxides  can  cause  regular  condensations 
of  aldehydes  or  ketones  in  vapor  phase. 

The  vapors  of  acetaldehyde,  or  of  paraldehyde,  passed  over  thoria  at 
about  260°  yield,  along  with  a  mixture  of  methane  and  carbon  mon- 
oxide resulting  from  the  decomposition  of  the  aldehyde,  a  liquid  con- 
taining water,  crotonic  aldehyde,  hexadienal,  without  doubt  associated 
with  a  certain  amount  of  octatrieneal.  Careful  hydrogenation  of  the 
liquid  over  nickel  at  180°,  gives  essentially  a  mixture  of  normal  butyl 
and  hexyl  alcohols.40 

The  vapors  of  acetone  passed  over  thoria  at  410-20°  give  consid- 
erable mesityl  oxide.*1 

Elimination  of  Water  from  a  Single  Molecule 

802.  We  have  seen    (308  and  310)  that  the  presence  of  certain 
catalysts  permits  the  addition  of  a  molecule  of  water  to  certain  doubly 
unsaturated  hydrocarbons,  the  products  usually  being  aliphatic  ke- 
tones.    The  inverse  reaction,  the  formation  of  a  doubly  unsaturated 
hydrocarbon  by  the  abstraction  of  a  molecule  of  water  from  a  ketone, 
can  be  realized  also.     It  has  been  found  that  the  vapor  of  methyl- 
isopropyl-ketone,  passed,  under  reduced  pressure,  over  kaolin  between 

"  KIPPING,  J.  Chem.  Soc.,  65,  498  (1894). 
87  SCHOLTZ,  Berichte,  28,  1726  (1895). 
"  VORLANDER  and  HOBOHM,  Berichte,  29,  1840  (1896). 

89  TIEMANN  and  KROGER,  Berichte,  26,  2691  (1893).—  Bull  Soc.  Chim.  (3),  9, 
798  (1893). 

40  SABATIER  and  GAUDION,  Compt.  rend.,  166,  632  (1918). 

41  MAILHE  and  DE  GODON,  Bull.  Soc.  Chim.  (4),  21,  63  (1917). 


289  DEHYDRATION  806 

400  and  600°,  gives  isoprene    (which  doubtless  results  from  the  is- 
omerization  of  3-methyl-butadiene(l,2)).42    We  would  have: 


/CH3  /CH3 

CH3  .CO  .CH(          -»  H2O  +  CH2  :  C  :  C(          -+  CH2  :  CH  . 

\CH3  \CH3  \CH3 


Condensations  of  Aldehydes  or  Ketones  with  Various 
Organic  Molecules 

803.  Condensations  with  elimination  of  water  comparable  to  cro- 
tonizations  can  frequently  take  place  between  aldehydes  or  ketones  and 
molecules  of  various  kinds,  nitro  compounds,  phenols,  esters,  indols, 
pyrrols,  etc.     These  reactions  are  most  frequently  brought  about  by 
the  usual  condensing  agents,  sulphuric  or  hydrochloric  acids,  zinc  chlo- 
ride, etc.,  or  ammonia  and  amines,  or  anhydrous  aluminum  chloride.    The 
products  are  generally  unsaturated  at  the  point  where  the  aldehyde  or 
ketone  groups  have  disappeared. 

Thus  benzaldehyde  condenses  with  nitromethane  in  the  presence  of 
zinc  chloride  to  give  a  nitro  derivative  of  phenyl-ethylene :  ** 

C6H6.CHO  +  CH3N02  =  H2O  +  C6H6.CH  :  CH.N02. 

804.  The  same  aldehyde  condenses  with  malonic  acid  or  its  esters 
to  form  benzylidene-malonic  acid  when  heated  in  presence  of  alcoholic 
ammonia  or  of  hydrochloric  acid : 44 

C6H5.CHO  +  H2C(C02R)2  =  H20  +  C6H6.CH  :  C(C02R)2 

From  equal  molecules  of  benzaldehyde  and  malonic  acid  warmed 
1.5  hours  to  55°  with  an  8%  alcoholic  ammonia  solution,  a  60%  yield 
of  the  condensed  acid  is  obtained.  The  ammonia  can  be  replaced  by 
ethyl-amine  or  piperidine.45 

805.  Acetone  condenses  with  pyrrol  on  the  addition  of  a  few  drops 
of  concentrated  hydrochloric  acid  to  give  a  crystalline  product,  the 
molecule  of  which  is  doubtless  quadruple  the  formula  given: 

C4H4N  +  CH3.CO.CH3  =  H20  +  C7H9N. 

48  EARLE  and  KTRIAKIDES,  U.  S,  Patent,  1,106,290. — /.  Soc.  Chem.  Ind.,  33, 
942  (1914). 

43  PRIEBS,  Annalen,  225,  321  (1884). 

44  CLAISEN,  Berichte,  14,  348  (1881). 

45  KNOEVENAGEL   German  patents,  94,132,  97,735  and  164,296  (1904). 


806  CATALYSIS  IN  ORGANIC  CHEMISTRY  290 

With  1  cc.  hydrochloric  acid,  14  g.  pyrrol  and  14  g.  acetone 
dissolved  in  80  cc.  alcohol  and  heated,  the  yield  is  about  95  %.46 

806.  Trioxymethylene  can  condense  with  benzene  or  its  homologs 
in  presence  of  anhydrous  aluminum  chloride  to  give  at  the  same  time 
diphenyl-methane  (or  a  homolog)  and  anthracene  :47 

4C6H6  +  (CH20)3  =  C6H6.CH2.C6H5  +  Ci4H10  +  3H2O  +  H2. 

Chloral  and  bromal  can  react  in  the  same  way  in  the  presence  of 
anhydrous  aluminum  chloride  on  various  aromatic  compounds  with 
the  elimination  of  water  and  the  loss  of  the  aldehyde  function.  This 
takes  place  with  benzene  and  its  homologs : 

2C6H6  +  CCls.CHO  =  H20  +  CCl3.CH(C6H5)2. 

Resorcine  (in  carbon  disulphide  solution)  gives  a  similar  reaction 
but  with  the  simultaneous  loss  of  hydrochloric  acid  :48 

2C6H4(OH)2  +  CC12CHO  =  H2O  +  HC1  +  CC12 :  C[C6H3(OH)2]2. 

Anisol  reacts  with  chloral  to  give  the  compound,  CC13.CH- 
(C6H4OCH3)2.49 

Naphthalene,  anthracene,  and  phenanthrene  react  in  an  analogous 
manner  with  chloral  and  bromal  in  the  presence  of  aluminum  chloride 
but  with  the  simultaneous  loss  of  water  and  halogen  hydride.  Thus 
naphthalene  gives  the  compound,  CC12 :  C(Ci0H7)2.50 


§  14.  —  ELIMINATION  OF  WATER  BETWEEN   ALDEHYDES 
OR  KETONES  AND  AMMONIA 

807.  Catalytic  oxides  can  bring  about  the  condensation  of  alde- 
hydes and  ammonia  in  various  ways. 

Acetaldehyde  and  ammonia  passed  over  alumina  below  300°  give  a 
certain  amount  of  pyrrol  by  simultaneous  dehydration  and  dehydro- 
genation: 51 

CH3.CHO  CH:CH\ 

+  NH3  =  2H20  +  H2  +  |  )NH. 

CH3.CHO  CH:CH/ 

46  CHELINTZEV  and  TRUNOV,  /.  Russian  Phys.  Chem.  Soc.,  48,  105  (1916);  C.  A. 
u,    452  (1917). 

47  FRANKFORTER  and  KOKATNUR,  /.  Amer.  Chem.  Soc.,  36,  1529  (1914). 

48  FRANKFORTER  and  DANIELS,  J.  Amer.  Chem.  Soc.  36,  1511  (1914). 

49  FRANKFORTER  and  KRITCHEVSKY,  J.  Amer.  Chem.  Soc.,  37,  2560  (1915). 
60  FRANKFORTER,  J.  Amer.  Chem.  Soc.,  37,  385  (1915). 


291  DEHYDRATION  811 

Acetaldehyde  and  benzaldehyde  carried  over  alumina  by  ammonia 
at  above  300°,  yield  a-  and  y-phenyl-pyridines: 51 

C6H5.CHO  +  2CH3.CHO  +  NH3  =  2H2  +  3H20  +  C5H4N.C6H3. 

808.  Aldehydes  and  ammonia  passed  over  thoria  at  420-50°  give, 
by  simultaneous   dehydration   and   dehydrogenation,   a   considerable 
proportion  of  nitriles: 

R.CHO  +  NH3  =  R.CN  +  H2O  +  H2. 

With  isovaleric  aldehyde,  the  yield  of  nitrile  reaches  40%  and 
equally  good  results  are  obtained  with  isobutyric,  propionic,  and  even 
benzoic  and  anisic  aldehydes.52 

809.  In  contact  with  thoria  at  300-400°,  ketones  and  ammonia 
give  ketimines.    With  benzophenone  the  yield  is  almost  theoretical.53 
We  have 

R\ 

R.CO.R'  +  NHa  =  H20  +       )C  :  NH. 

R/ 

§15.  — ELIMINATION   OF  WATER  BETWEEN  ALDEHYDES 
AND  HYDROGEN   SULPHIDE 

810.  In  contact  with  alumina  below  300°,  acetaldehyde  condenses 
with  hydrogen  sulphide  with  simultaneous  dehydration  and  dehydro- 
genation to  give  thiophene:*1 

2CH3CHO  +  H2S  =  H2  +  2H2O  +  C4H4S 

§  16.  — DEHYDRATION  OF  AMIDES 

811.  The  dehydration  of  amides  to  nitriles  can  be  effected  by  ap- 
propriate catalysts.    The  amide  mixed  with  the  catalyst  is  heated  to 
250-60°  for  4  hours  in  a  flask  fitted  with  a  reflux  condenser.     Four 
parts  by  weight  of  catalyst  are  used  to  one  of  amide.64 

Acetamide  gave  the  following  yields  of  acetonitrile: 

With  alumina    . 68  % 

lamp  black 68 

pumice      65 

powdered  glass 65 

sand      52 

51  CHICHIBABIN,  J.  Russian  Phys.  Chem.  Soc.,  47,  703  (1915);  C.  A.,  gt  2512 
(1915). 

w  MAILHE  and  DE  GODON,  Compt.  rend.,  166,  215  (1918). 

63  MIGNONNAC,  Compt.  rend.,  169,  237  (1919). 

64  BOEHNER  and  ANDREWS,  /.  Amer.  Chem.  Soc.,  38,  2503  (1916). 


812  CATALYSIS  IN  ORGANIC  CHEMISTRY  292 

But  better  yields  are  obtained  by  carrying  the  amide  in  a  current 
of  air  over  the  catalyst  heated  to  420°,  the  yields  being:65 

With  pumice 91.5 

alumina 82 

sand 86.5 

graphite 75.5 

812.  The  same  process  can  be  applied  to  nascent  amides  furnished 
by  the  vapors  of  the  acid  with  ammonia  in  excess  in  the  presence  of 
alumina  or  thoria  at  around  500°.     Alumina  gives  the  best  results. 
Starting  with  acetic  acid  an  85%  yield  of  the  nitrile  is  obtained.66 

813.  We  may  put  along  side  of  the  catalytic  dehydration  of  amides 
to  nitriles,  the  action  of  ammonia  gas  on  the  chlorides  of  acids  in  the 
presence  of  catalytic  oxides.     The  amide  formed  is  immediately  de- 
hydrated to  the  nitrile. 

The  mixture  of  ammonia  and  the  acid  chloride  is  passed  over 
alumina  at  490-500°  and  water  and  hydrogen  chloride  are  eliminated: 

R.COC1  +  NH3  =  R.CN  +  H20  +  HC1. 

High  yields  of  the  nitriles  are  obtained  in  this  way  from  propionyl, 
isobutyryl,  isovalyryl  and  benzoyl  chlorides.  As  the  ammonia  gas  is 
used  in  excess,  ammonium  chloride  is  formed  and  deposits  in  crystals 
in  a  receiver  placed  at  the  end  of  the  reaction  tube.67 

§  17.  — DEHYDRATION   OF  OXIMES 

814.  The  aldoximes  which  are  isomeric  with  the  amides  can  be 
transformed  into  nitriles  in  the  same  way.    The  vapors  of  the  aldoximes 
are  passed  over  alumina  or  thoria  maintained  at  350-60°  and  give 
the  nitriles.     Isovalerald-oxime  gave  isovalero-nitrile  and  oenanthald- 
oxime  gave  hexyl  cyanide.     The  ketoximes,  when  submitted  to  the 
action  of  these  dehydration  agents,  undergo  a  complex  reaction  in 
which  nitriles  with  one  less  carbon  are  formed.68 

§  18.  — DIRECT  SULPHONATION  OF    AROMATIC 
COMPOUNDS 

815.  The  direct  sulphonation  of  aromatic  compounds  by  means  of 
concentrated  sulphuric  acid  corresponds  to  the  elimination  of  water  and 
can  be  facilitated  or  modified  by  the  presence  of  certain  catalysts. 

65  BOEHNER  and  WARD,  J.  Amer.  Chem.  Soc.,  38,  2505  (1916). 

66  VAN  EPPS  and  REID,  J.  Amer.  Chem.  Soc.,  38,  2128  (1916). 
"  MAILHE,  Bull.  Soc.  Chim.  (4),  23,  380  (1918). 

"  MAILHE  and  DE  GODON,  Bull  Soc.  Chim.  (4),  23,  18  (1918). 


293  DEHYDRATION  817 

The  addition  of  1  part  of  iodine  to  240  parts  of  benzene  warmed 
with  584  parts  sulphuric  acid  brings  about  complete  sulphonation  in 
5  hours;  the  iodine  is  readily  recovered.59  60 

816.   The  catalyst  most  commonly  employed  is  mercuric  sulphate. 

Benzoic  acid  heated  with  sulphuric  acid  alone  gives  only  the  meta 
and  para  derivatives,  but  in  the  presence  of  mercuric  sulphate,  the 
ortho  is  obtained.61 

Anthraquinone  gives  only  the  /3-monosulphonic  acid  with  sulphuric 
acid  alone,  or  the  2,6  and  2,7  disulphonic  acids,  when  fuming  sul- 
phuric is  used. 

By  heating  to  130°  with  0.5  part  mercury  to  110  parts  sulphuric 
acid  and  29  parts  sulphur  trioxide,  the  a-monosul  phonic  acid  is  ob- 
tained. At  160°  with  1  part  mercury  to  200  parts  sulphuric  acid  and 
40  parts  of  the  trioxide  the  disulphonic  acids  (1,  5),  (1,  6),  (1,  7),  and 
(1,  8)  are  obtained.62  63 

Vanadium  sulphate  has  been  proposed  for  aiding  the  sulphonation 
of  pyridine.64 

§  19.  —  CONDENSATIONS  BY  ELIMINATING  MOLECULES 

OF  ALCOHOLS 

817.  It  is  convenient  to  consider  reactions  in  which  molecules  of 
aliphatic  alcohols  are  eliminated  along  with  those  in  which  water  is 
abstracted.  Anhydrous  aluminum  chloride  is  specially  suitable  as  a 
catalyst  for  such  condensations. 

Ethyl  ether  reacts  with  benzene  in  the  presence  of  aluminum  chlo- 
ride to  form  ethyl-benzene  with  the  elimination  of  alcohol  :8B 

C6H6  +  (C2H5)20  =  C2H5.OH  +  C6H6.C2H6. 

59  HEINEMANN,  English  patent,  12,260  of  1915.  —  /.  Soc.  Chem.  Ind.,  35,  1008 
(1916). 

80  According  to  RAY  and  DEY  (J.  Chem.  Soc.  117,  1405  (1920))  iodine  influences 
the  sulphonation  of  many  compounds  notably  that  of  benzoic  acid,  the  sulphonic 
acid  group  taking  the  ortho  position  under  the  influence  of  iodine  instead  of  meta 
and  para:  toluene,  chlor-  and  brombenzenes  are  sulphonated  in  para  position 
only  instead  of  ortho  and  para.  —  E.  E.  R. 

61  DIMMROTH  and  VON  SCHMAEDEL,  Berichte,  40,  2411  (1907). 

62  ILJINSKY,  Berichte,  36,  4194  (1914). 

63  In  the  absence  of  mercury  salts,  a  very  small  proportion,  about  3%  of  a 
sulphonic  acid  is  formed  along  with  the  beta.    The  presence  of  the  mercury  salt 
does  not  seem  to  affect  the  rate  of  sulphonation  in  the  beta  position  but  increases 
the  rate  of  sulphonation  in  the  alpha  position  so  enormously  that  the  operation 
can  be  carried  on  at  much  lower  temperatures  and  with  weaker  oleum  under  which 
conditions  the  formation  of  the  /3-sulphonic  acid  is  slow.  —  E.  E.  R. 

84  FARBW.  v.  F.  BAYER  &  Co.,  German  patent,  160,104. 
'JANNASCH  and  BARTELS,  Berichte,  31,  1716  (1898). 


818  CATALYSIS  IN  ORGANIC  CHEMISTRY  294 

818.  Under  the  same   conditions  benzene  reacts  with  the  chlor- 
methyl  ethers  by  the  elimination  of  alcohol  to  form  benzyl  chloride  along 
with  some  of  the  ether  C6H5.CH2.O.R(889).     We  have:66 

C6H6  +  C1CH2.O.R  =  ROH  +  C6H5.CH2C1. 

alcohol 

819.  Ethyl  nitrate  with  benzene  and  aluminum  chloride,  gives  a 
vigorous  reaction  which  leads  to  nitrobenzene  and  the  separation  of 
alcohol  :67 

C6H6  +  02N.O.C2H5  =  C6H5.N02  +  C2H5.OH. 

66  SOMMELET,  Compt.  rend.,  157,  1443  (1913). 

67  BOEDTKER,  Bull  Soc.  Chim.  (4),  3,  726  (1908). 


CHAPTER  XVIII 
DECOMPOSITION   OF  ACIDS 

820.  The  aliphatic  acids  are  very  stable  under  the  action  of  heat, 
except  formic,  which  is  decomposed  by  heat  under  many  conditions. 
We  will  take  up  separately  the  catalytic  decomposition  of  formic  acid 
and  then  the  decomposition  of  other  aliphatic  and  aromatic  acids 
under  the  influence  of  metals  and  of  oxides.    The  action  of  the  oxides 
leads  to  important  applications  which  will  be  studied  in  succession,  the 
preparation  of  symmetrical  ketones,  of  mixed  ketones  and  of  aldehydes. 

DECOMPOSITION   OF  FORMIC  ACID 

821.  The  decomposition  of  formic  acid  by  heat  may  go  in  several 
distinct  directions,  either  by  the  separation  of  carbon  dioxide: 

H.C02H  =  C02  +  H2  (1) 

or  by  the  elimination  of  water: 

H.C02H  =  CO  +  H20  (2) 

or  by  the  simultaneous  elimination  of  water  and  carbon  dioxide  from 
two  molecules: 

2H .  C02H  =  H.CO.H  +  CO2  +  H2O.  (3) 

formaldehyde 

If  reactions  (1)  and  (3)  coexist,  the  nascent  hydrogen  from  (1) 
may  sometimes  act  on  the  formaldehyde  produced  in  (3)  to  trans- 
form it  into  methyl  alcohol.  We  will  then  have  : 

3H .  CO2H  =  CH3 .  OH  +  2C02  +  H2O.  (4) 

The  presence  of  a  given  catalyst  will  have  the  effect  of  turning 
the  decomposition  either  into  one  of  these  directions  or  into  several 
at  the  same  time,  by  lowering  more  or  less  the  temperature  of  the 
decomposition. 

1  BERTHELOT,  Ann.  Chim.  Phys.  (4),  18,  42  (1869).  —  SAINTE-CLAIRE-DEVILLE 
and  DEBRAY,  Compt.  rend.,  78,  1782  (1874).  —  BLACKADDER,  Zeit.  phys.  Chem., 
81,  385  (1912). 

295 


822  CATALYSIS  IN  ORGANIC  CHEMISTRY  296 

822.  Reaction    (1)  which  is  a  dehydrogenation,  is  produced  at 
the  ordinary  temperature  by  rhodium  black,1  or  by  palladium  black.2 

Reaction  (2)  which  is  a  dehydration  is  brought  about  by  sub- 
stances that  take  up  water,  sulphuric  acid  which  acts  below  100°,  dry 
oxalic  acid  above  105°  or  anhydrous  sodium  and  potassium  formates 
above  1500.3 

823.  Sabatier  and  Mailhe  have  studied  the  decomposition  of  for- 
mic acid  under  the  influence  of  various  catalysts,  including  finely 
divided  metals,  anhydrous  oxides  and  some  other  substances.4     Com- 
parisons have  been  made  under  analogous  experimental  conditions, 
the  addition  of  the  formic  acid  being  at  about  0.27  g.  per  minute  and 
the  pulverulent  solid  catalyst  forming  a  layer  50  cm.  long  in  a  hor- 
izontal Jena  glass  tube  heated  to  a  known  temperature. 

The  tube  without  catalyst  gave  a  negligible  decomposition  below 
300°,  while  at  340°  2.6  cc.  of  gas  was  collected  per  minute,  chiefly  a 
mixture  of  hydrogen  and  carbon  dioxide  (reaction  1)  with  a  few  per- 
cent of  carbon  monoxide  (reaction  2). 

824.  The  catalysts  studied  can  be  divided  into  three  groups  : 
1st.  Dehydrogenating  Catalysts.    These  are  the  ones  that  cause  re- 
action  (1)  almost  exclusively,  doubtless  because  they  give  rise  to  a 
temporary  compound  with  one  of  the  products,  either  hydrogen  or 
carbon  dioxide.     The  metals  doubtless  combine  with  the  hydrogen  : 

Palladium  (sponge)  acts  at  110°  and  produces  total  decomposi- 
tion at  245°. 

Platinum  (sponge)  begins  to  decompose  it  at  120°,  the  reaction 
being  complete  at  215°. 

Reduced  copper  (light  violet)  evolves  at  190°  278  cc.  of  gas 
containing  equal  amounts  of  hydrogen  and  carbon  dioxide. 

Reduced  nickel  at  280°  disengages  290  cc.  gas  containing  only 
traces  of  carbon  monoxide. 

Finely  divided  cadmium,  prepared  by  reducing  the  oxide,  gives 
325  cc.  gas  per  minute  at  280°. 

Stannous  oxide  begins  to  act  above  150°,  while  at  285°  it  evolves 
172  cc.  of  gas,  being  slowly  reduced  to  small  globules  of  tin  which  con- 
tinue the  catalysis.  The  gas  contains  a  small  excess  of  carbon  dioxide 
due  to  reaction  (3)  which  takes  place  to  a  slight  extent. 

An  analogous  result  is  produced  by  zinc  oxide  where  the  temporary 
production  of  zinc  carbonate  is  doubtless  the  cause  of  the  reaction  : 
it  begins  to  act  at  about  190°  and  at  230°  disengages  172  cc.  of  gas 
containing  51  %  of  carbon  dioxide  and  49  %  of  hydrogen  by  volume. 

2  ZELINSKY  and  GLINKA,  Berichte,  44,  2305  (1911). 

3  LOBIN,  Compt.  rend.,  82,  750  and  Bull  Soc.  Chim.  (2),  25,  517  (1876). 

4  SABATIER  and  MAILHE,  Compt.  rend.,  152,  1212  (1911). 


297  DECOMPOSITION  OF  ACIDS  826 

The  production  of  formaldehyde  according  to  equation  (3)  amounts  to 
2%.5    At  245°  this  may  be  raised  to  12%  of  formaldehyde.6 

825.  2nd.  Dehydrating  Catalysts.     Reaction   (2)  takes  place  ex- 
clusively with  titania  above  170°,  and  at  320°  180  cc.  of  practically 
pure  carbon  monoxide  is  collected  per  minute. 

The  blue  oxide  of  tungsten  (715)  acts  the  same  way :  at  270°  it 
gives  195  cc.  carbon  monoxide  practically  pure. 

The  reaction  goes  in  the  same  direction,  but  with  reaction  (3)  as  a 
side  reaction  to  a  slight  extent,  that  is  formaldehyde  is  produced 
equivalent  to  the  carbon  dioxide  without  hydrogen,  with  alumina, 
silica,  zirconia,  and  uranous  oxide,  U02. 

With  alumina;  the  decomposition,  which  begins  at  about  234°, 
yields  carbon  monoxide  containing  6%  of  the  dioxide.  Reaction  (2) 
dominates  but  about  10%  is  decomposed  according  to  (3)  giving 
formaldehyde. 

At  340°  the  disengagement  of  gas  reaches  192  cc.  per  minute,  but 
the  gas  then  contains  a  little  hydrogen  resulting  from  the  partial 
decomposition  of  the  formaldehyde. 

Silica,  which  is  less  active  than  alumina,  gives  about  3%  of 
reaction  (3). 

At  340°,  zirconia  gives  144  cc.  gas  containing  5%  of  carbon 
dioxide:  reaction  (3)  takes  place  to  an  extent  of  10%. 

With  uranous  oxide,  reaction   (3)  is  almost  as  important  as   (2). 

826.  3rd.  Mixed  Catalysts.    These  are  the  most  numerous  of  all. 
They  produce  reactions  (1)  and  (2)  simultaneously,  usually  with  (3) 
as  a  minor  side  reaction. 

This  is  what  takes  place  with  thoria.  The  decomposition  shown  by 
a  slight  evolution  of  gas,  begins  around  230.°  It  is  still  quite  slow  at 
250°,  and  gives  a  gas  which  contains  75  %  carbon  monoxide,  15  %  car- 
bon dioxide,  and  10  %  hydrogen;  the  condensed  liquid  contains  formal- 
dehyde. These  figures  show  that  of  100  molecules  of  formic  acid,  79 
undergo  reaction  (2),  the  other  21  being  equally  divided  between  (1) 
and  (3). 

Elevation  of  temperature  modifies  the  conditions  of  the  decompo- 
sition which  is  more  and  more  rapid.  At  320°  the  gas  amounts  to 
120  cc.  per  minute  and  the  carbon  dioxide  reaches  45  %  and  the  liquid 
contains  considerable  methyl  alcohol,  resulting  from  the  intervention  of 
reaction  (4)  which  may  be  regarded  as  a  reduction  of  formic  acid  by 
formaldehyde: 

H.C02H  +  H.CO.H  =  C02  +  CH8.OH. 

6  SABATIER  and  MAILHE,  Compt.  rend.,  152,  1212  (1911). 
•  HOFMANN  and  SCHIBSTED,  Berichte,  51,  1398  (1918). 


827  CATALYSIS  IN  ORGANIC  CHEMISTRY  298 

The  amount  of  methyl  alcohol  increases  above  350°  and  as  formalde- 
hyde is  then  partially  decomposed  into  carbon  monoxide  and  hydro- 
gen, the  proportion  of  hydrogen  increases  while  that  of  carbon  dioxide 
decreases.  At  375°,  the  gas  is  144  cc.  per  minute  containing  only  33  % 
carbon  dioxide.  The  condensate  contains  methyl  alcohol. 

827.  For  certain  mixed  catalysts,  reaction  (1)  predominates;   this 
is  the  case  with  the  blue  oxide  of  molybdenum,  Mo2C>2,  resulting  from 
the  reduction  of  molybdic  oxide  by  the  formic  acid  at  340°.    The  de- 
composition, already  clean  at  105°,  gives  at  340°,  325  cc.  of  gas  con- 
taining only  5%  carbon  monoxide.     Of  12  molecules  of  the  acid,  9 
decompose  according  to  reaction   (1),  2  according  to   (3)  and  1  ac- 
cording to  (2). 

Ferrous  oxide,  an  active  catalyst,  and  lime  and  broken  Jena  glass, 
mediocre  catalysts,  favor  reaction  (1)  decidedly. 

828.  The  two  reactions  (1)  and  (2)  are  of  about  equal  importance 
with  powdered  white  glass  which  acts  at  240°. 

The  dehydration  reaction  (2)  predominates  as  is  indicated  by  the 
proportion  of  carbon  dioxide  being  less  than  33  %,  with  a  large  number 
of  substances  whose  absolute  activities  differ  greatly,  thus: 

Powdered  pumice  liberates  at  340°  .    .        4  cc.  per  minute. 

Magnesia 10 

Charcoal  from  light  wood 95 

Light  chromic  oxide 150 

Black  vanadium  oxide 215 

Manganous  oxide      225 

Beryllium  oxide 250 

Reaction  (3)  takes  place  more  or  less  with  all  of  these. 


DECOMPOSITION   OF  MONOBASIC  ORGANIC  ACIDS 

829.   In  the  action  of  heat  on  monobasic  organic  acids  we  find  the 
three  types  of  reactions  given  above  for  formic  acid  (821),  namely: 
1st.  Elimination  of  carbon  dioxide: 

R.CO.OH  =  C02  +      EH  (1) 

hydrocarbon 

2nd.  Separation  of  water  alone,  which  can  take  place  with  primary 
or  secondary  acids  only: 

RR'.CH.CO.OH  =  H20  +  RR'C  ;  CO  (2) 

ketene 

3rd.  Simultaneous  elimination  of  water  and  carbon  dioxide  from 
two  molecules  of  acid,  giving  a  symmetrical  ketone: 


299  DECOMPOSITION  OF  ACIDS  831 

2R  .CO  .OH  =  C02  +  H20  +  R.CO.R  (3) 

ketone 

Reaction  (2)  is  realized  only  exceptionally,  as  in  the  case  of  the  ac- 
tion of  an  incandescent  platinum  spiral  on  the  vapors,  not  of  acetic 
acid  but  of  acetanhydride,  giving  the  ketene,  CH  :  CO,7  because  the 
ketenes  that  are  formed  are  very  unstable  and  tend  to  polymerize 
ending  up  with  carbonaceous  substances. 

Reactions  (1)  and  (3)  are  of  great  importance. 

830.  Without  the  aid  of  a  catalyst  these  two  reactions  take  place 
simultaneously  at  a  dull  red  heat:  but  the  hydrocarbon  and  even  the 
ketone  are  more  or  less  destroyed  and  a  complex  pyrogenetic  mixture 
results.    The  presence  of  a  catalyst,  either  a  finely  divided  metal  or  an 
oxide,  orients  the  reaction  and  lowers  the  reaction  temperature. 

With  aliphatic  acids,  reaction  (1)  is  the  most  difficult  to  effect  and 
is  obtained  only  with  difficulty  by  the  use  of  finely  divided  metals. 
On  the  contrary,  reaction  (3)  is  easily  brought  about  by  the  aid  of 
oxide  catalysts  and  leads  to  a  practical  method  for  the  preparation  of 
symmetrical  ketones. 

Aromatic  and  cyclic  acids  frequently  give  reaction  (1)  under  the 
action  of  heat  alone  so  that  the  aid  of  catalysts  is  often  superfluous. 
However,  the  presence  of  suitably  chosen  catalysts  can  either  accelerate 
reaction  (1)  or  substitute  for  it,  partially  or  entirely,  reaction  (3) 
which  would  not  take  place  in  their  absence.  But  among  the  aro- 
matic acids  it  is  necessary  to  distinguish  between  those  in  which  the 
carboxyl  is  joined  directly  to  the  nucleus  and  those  in  which  the  car- 
boxyl  is  in  a  side  chain.  For  the  latter,  e.g.  phenyl-acetic  acid,  CeHs.  = 
CH2.COOH,  reaction  (3)  is  easily  realized  by  the  aid  of  catalytic 
oxides  as  is  the  case  with  aliphatic  acids. 

For  the  former,  e.g.  benzoict  CeH6.COOH,  and  the  toluic  acids,  re- 
action (1)  is  the  one  that  always  tends  to  take  place,  reaction  (3) 
being  very  difficult  to  obtain,  at  least  with  the  aromatic  acids  alone. 

SIMPLE  ELIMINATION  OF  CARBON  DIOXIDE 

831.  In  the  case  of  aliphatic  acids  this  is  accomplished  more  or  less 
by  finely  divided  metals. 

Finely  divided  copper  commences  to  decompose  the  vapors  of  acetic 
acid  at  260°,  and  an  evolution  of  gas  is  obtained,  slow  at  first  but 
quite  regular  at  390-410°,  containing  7  volumes  of  carbon  dioxide  to  1  of 
methane.  The  formation  of  some  acetone  is  observed.  Reactions  (1) 
and  (3)  are  catalyzed  and  the  composition  of  the  gas  shows  that  of  13 

7  WILSMORE,  J.  Chem.  Soc.,  91,  1938  (1901). 


832  CATALYSIS  IN  ORGANIC  CHEMISTRY  300 

molecules  of  the  acid,  1  has  decomposed  according  to  reaction  (1)  and 
12  have  given  acetone. 

832.  Reduced  nickel  causes,  slowly  below  240°,  rapidly  above  320°, 
an  analogous  decomposition.    The  gas  contains  50%  of  methane  and 
reaction  (1)  seems  to  have  taken  place  exclusively,  but  a  portion  of 
the  acids  is  decomposed  into  carbonaceous  substances  which  are  de- 
posited on  the  metal.8 

833.  Other  aliphatic  acids  give  analogous  results.    The  action  of 
copper  is  slow.    That  of  nickel  is  much  more  rapid:  at  230°,  propionic 
acid  is  broken  down  into  carbon  dioxide  and  ethane  which  is  largely 
decomposed    into    methane,   carbon  and    hydrogen.     No   ketone   is 
formed,  but  a  part  of  the  acid  is  reduced  to  the  aldehyde.    At  250°, 
butyric  acid  gives  analogous  results,  so    do  isobutyric  and  caproic.9 

834.  With  aromatic  acids  the  decomposition  into  carbon  dioxide 
and  hydrocarbon  is  usually  quite  easy. 

The  vapors  of  benzoic  acid  carried  along  by  carbon  dioxide  over 
reduced  copper  at  550°,  are  totally  decomposed  into  benzene  and  car- 
bon dioxide. 

Over  nickel,  or  over  the  oxide  which  is  rapidly  reduced  at  that 
temperature,  the  benzene  produced  is  almost  entirely  broken  up  with 
the  deposition  of  carbon  and  the  liberation  of  hydrogen  and  methane. 
Under  the  same  conditions,  reduced  iron  gives  benzene,  which  is  par- 
tially destroyed,  and  some  diphenyl.10 

835.  In  contact  with  copper  powder,  coumanic  acid  is  regularly 
transformed  into  y-pyrone:11 

CO  CO 

HC          CH  HC         CH 

-»     •  •      +C02. 

HC          C.COOH      HC         CH 

v       v     - 

836.  The  presence  of  alkaloids  favors  the  decomposition  of  the 
carboxy-camp/ior  acids  at  70°  into  camphor  and  carbon  dioxide.    With 
an  inactive  alkaloid,  in  polarized  light,  the  dextro  and  laevo  acids  are 
decomposed  at  the  same  rate;   with  an  active  alkaloid,  the  velocities 
are  different.     Thus  with  quinine  a  difference  of  46%  is  found.12 

The  conditions  of  this  decomposition  in  the  presence  of  quinoline, 

8  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  467  (1905). 
»  MAILHE,  Bull.  Soc.  Chim.  (4),  5,  616  (1909). 

10  SABATIER  and  MAILHE,  Compt.  rend.,  159,  217  (1914). 

11  WILLSTATTER  and  PUMMERER,  Berichte,  38,  1461  (1908). 
»  FAJANS,  Zeit.  physik.  Chem.,  73,  25  (1910). 


301  DECOMPOSITION  OF  ACIDS  839 

pyridine,  piperidine,  and  of  other  amines,  benzyl-amine,  allyl-,  iso- 
amyl-amine,  etc.,  have  been  studied  in  detail,  in  various  solvents  at  80° 
with  the  result  that  the  formation  of  a  complex  by  the  acid  and  the 
amine  appears  to  be  the  cause  of  the  catalysis  in  every  case.13 

SIMULTANEOUS  ELIMINATION  OF  WATER  AND 
CARBON   DIOXIDE 

I.  Preparation  of  Symmetrical  Ketones 

837.  This  is  the  reaction  that  is  specially  catalyzed  by  metallic 
oxides. 

It  is  derived  in  fact  from  the  old  method  of  preparing  symmetrical 
ketones  by  calcining  at  a  red  heat  the  calcium  or  barium  salts  of  mon- 
obasic organic  acids: 

(R.C02)2Ba  =  R.CO.R  +  BaCO3. 

Squibb  conceived  the  idea  of  transforming  this  reaction  into  a  cat- 
alytic one.  By  passing  the  vapors  of  acetic  acid  over  barium  carbonate 
heated  to  about  500°,  a  regular  and  continuous  decomposition  of  the 
acetic  acids  into  acetone,  water  and  carbon  dioxide  is  obtained: 

2CH3.C02H  =  CHs.CO.CHs  +  C02  +  H2O. 

The  process  which  gives  a  yield  of  better  than  90  %  has  been  used 
industrially.  The  carbonates  of  all  the  metals  whose  acetates  give 
acetone  on  calcination  may  be  used.14  We  have  studied  above  (161) 
the  mechanism  of  this  reaction. 

838.  Ipatief  described  an  analogous  formation  when  he  used  zinc 
oxide  or  carbonate  or  the  carbonates  of  calcium,  barium  and  strontium. 
Acetic  acid  gives  acetone,  and  propionic  acid,  diethyl-ketone.1* 

839.  Calcium  Carbonate.    This  is  an  excellent  catalyst  for  acetic 
acid,  a  short  column  at  450°  is  sufficient  to  transform  the  acid  com- 
pletely into  practically  pure  acetone  with  the  evolution  of  nothing  but 
carbon  dioxide  and  water. 

With  propionic  acid,  the  yield  of  diethyl-ketone  is  very  satisfactory, 
some  propionic  aldehyde  is  obtained  and  the  gas  contains  a  little  eth- 
ylene.  This  formation  of  the  aldehyde  increases  with  the  complexity  of 
the  molecule  and  appears  to  be  correlative  to  the  production  of  the 
unsaturated  hydrocarbon.  We  have: 

CnH2n+1CO.OH  =  CnH2n  +  H.CO.OH. 

hydrocarbon       formic  acid 

18  BREDIQ  and  JOYNER,  Zeit.  f.  Elektrochem.,  24,  285  (1918). 
14  SQUIBB,  J.  Amer.  Chem.  Soc.,  17, 187  (1895),  and  18,  231  (1896).  — CONROT, 
Rev.  gen.  Sci.,  13,  563  (1902). 

"  IPATIEF  and  SCHULMANN,  J.  Russian  Phys.  Chem.  Soc.,  36,  764  (1904). 


840  CATALYSIS  IN  ORGANIC  CHEMISTRY  302 

The  formic  acid  thus  produced  can  break  up  at  once  into  COa  +  EU 
or  into  CO  +  H^O  (821),  but  it  can  act  also  on  the  acid  that  is  being 
used  reducing  it  to  the  aldehyde  (851). 

The  secondary  reactions,  still  more  important  for  butyric  acid,  are 
exaggerated  with  isobutyric  and  isovaleric  acids. 

The  calcium  carbonate  used  is  blackened  by  the  decomposition  of  a 
small  portion  of  the  acid,  but  nevertheless  conserves  its  catalytic  activ- 
ity almost  indefinitely  and  remains  as  carbonate  for  the  most  part.16 

Benzoic  acid  is  scarcely  attacked  till  about  550°,  and  gives  chiefly 
benzene  and  carbon  dioxide  with  only  a  little  benzophenone  and  traces 
of  anthraquinone.17 

The  same  difficulty  is  encountered  with  the  typical  aromatic  acids 
in  which  the  carboxyl  is  united  directly  to  the  nucleus,  such  as  ortho, 
meta,  and  paratoluic  acids  and  the  naphthoic  acids. 

On  the  contrary,  aromatic  acids  in  which  the  carboxyl  is  in  a  side 
chain,  such  as  phenyl-acetic,  and  phenyl-propionic  acids  can  be  advan- 
tageously transformed  into  the  corresponding  symmetrical  ketones  at 
430-70°. 

840.  Among  the  metallic  oxides  the  most  suitable  for  the  produc- 
tion of  ketones  are  thoria  and  manganous  oxide.    It  is  sufficient  to  pass 
the  vapors  of  the  acid  over  a  layer  of  the  oxide,  usually  below  450°. 

Alumina.  Alumina  gives  very  good  results  with  acetic,  not  quite 
so  good  with  propionic  and  quite  poor  with  isobutyric.1*  With  benzole 
only  a  slow  decomposition  into  benzene  is  effected. 

Chromic  Oxide.  The  results  are  analogous  to  those  obtained  with 
alumina. 

Uranium  and  Zirconium  Oxides.  These  give  nearly  the  same  re- 
sults but  their  activity  diminishes  quite  rapidly. 

Lime.  Lime  acts  as  the  carbonate.  When  it  is  used  at  400°,  it  is 
possible  to  observe  the  formation  of  the  intermediate  salt,  the  decom- 
position of  which  furnishes  the  ketone  and  which  is  decomposed  only 
above  420°  for  the  acetate  and  460°  for  the  butyrate.  The  temperatures 
reached  can  account  for  some  decomposition  of  the  ketones  formed. 

841.  Zinc  Oxide.    With  zinc  oxide,  the  acetate  is  decomposed  above 
280°  and  very  rapidly  at  340°;  the  production  of  acetone  is  therefore 
very  easy.     The  difficulty  of  forming  the  ketone  increases  with  the 
molecular  weight  of  the  acid  and  is  partly  due  to  the  volatility  of  the 
zinc  salt.    Benzoic  acid  is  not  attacked  below  500°  and  then  gives  only 
benzene. 

16  SABATIER  and  MAILHE,  Bull.  Soc.  Chim.  (4),  13,  319  (1913)  and  Compt.  rend., 
156,  1730  (1913). 

17  SABATIER  and  MAILHE,  Compt.  rend.,  159,  217  (1914). 
"  SENDERENS,  Bull.  Soc.  Chim.  (4),  3,  824  (1908). 


303  DECOMPOSITION  OF  ACIDS  844 

842.  Cadmium  Oxide.    This  is  slowly  reduced  by  the  acid  vapors 
but  without  the  activity  being  diminished  by  the  formation  of  the 
metal  which  can  be  seen  sublimed  in  the  tube.     At  400-450°  it  can 
readily  transform  acetic,  propionic,  butyric  and  valeric  adds  into  their 
symmetrical  ketones;  the  results  are  not  so  good  with  branched  chain 
acids  as  isobutyric  and  isovaleric,  with  which  the  gas  evolved  is  no 
longer  pure  carbon  dioxide  but  contains  considerable  amounts  of  the 
unsaturated  hydrocarbons,  carbon  monoxide  and  hydrogen.19 

It  acts  at  450°,  and  violently  at  500°,  on  the  vapors  of  benzoic  acid 
to  give  benzene,  the  reduction  of  the  oxide  hardly  modifying  the 
catalysis.20 

843.  Oxides  of  Iron.    Ferrous  oxide  resulting  from  the  calcination 
of  the  oxalate  as  well  as  ferric  oxide  which  is  rapidly  reduced  to  the 
ferrous,  can  give  good  results  with  aliphatic  acids  at  450-90°.     The 
yield  of  ketone  is  excellent  with  acetic  or  propionic,  good  with  caprylic 
and  poor  with  isobutyric  or  isovaleric  acid.21 

The  immediate  formation  of  a  ferrous  compound  is  the  basis  of  a 
process  for  the  preparation  of  ketones  by  heating  an  acid  with  10% 
of  its  weight  of  iron  scale  :  this  works  well  for  the  higher  fatty  acids 
from  lauric  up  to  melissic.  Thus  stearic  acid  gives  80  %  of  the  ketone. 
The  results  are  not  so  good  with  olelc,  elaidic,  and  brassidic  and  are 
poor  with  the  lower  acids,  acetic,  butyric,  etc.,  as  well  as  with  phenyl- 
acetic,  benzoic,  suberic,  and  sebacic.22 

With  benzoic  acid  at  550°,  ferric  oxide  acts  like  iron  (834),  but  its 
simultaneous  reduction  causes  the  formation  of  a  certain  amount  of 
phenol  which  results  from  the  oxidation  of  the  benzene  formed.23 

844.  Thoria.    Thoria  of  which  the  valuable  qualities  of  constant 
activity  and  ready  revivification  have  been  mentioned  in  connection 
with  the  dehydration  of  alcohols   (708),  gives  excellent  results  with 
various  monobasic  aliphatic  acids  and  enables  us  to  prepare  with  good 
yields,  acetone,  diethyl-ketone,  dipropyl-ketone,  diisopropyl-ketone,  diiso- 
butyl-ketone,  dibutyl-ketone,  etc.,  as  well  as  ketones  derived  from  aro- 
matic acids  in  which  the  carboxyl  is  not  joined  immediately  to  the 
nucleus,  such  as  phenyl-acetic,  /3-phenyl-propionic,  etc.24 

Benzoic  acid  is  only  slowly  attacked  by  thoria  even  at  550°  and 
then  is  only  decomposed  into  benzene  and  carbon  dioxide.25 

19  MAILHE,  Bull.  Soc.  Chim.  (4),  13,  666  (1913). 

20  SABATIER  and  MAILHE,  Compt.  rend.,  159,  217  (1914). 

21  MAILHE,  Compt.  rend.,  157,  219  (1913). 

22  EASTERFIELD  and  TAYLOR,  /.  Chem.  Soc.,  99,  2298  (1911). 

23  SABATIER  and  MAILHE,  Compt.  rend.,  159,  217  (1914). 

24  SENDERENS,  Ann.  Chim.  Phys.  (8),  18,  243  (1913). 

25  SABATIER  and  MAILHE,  Compt.  rend.,  159,  217  (1914). 


845  CATALYSIS  IN  ORGANIC  CHEMISTRY  304 

845.  Manganous  Oxide.     This  oxide  prepared  by  calcining  the 
precipitated  carbonate  in  the  vapor  of  methyl  alcohol,  is  on  account  of 
its  low  price  and  its  great  activity,  very  useful  for  the  preparation  of 
ketones  at  400-450°.     The  carbonaceous  deposits  do  little  harm  and 
the  same  lot  of  oxide  has  been  used  in  22  different  preparations.    In 
the  case  of  slightly  volatile  acids,  carbon  dioxide  is  used  to  carry  their 
vapors  along. 

The  yields  of  symmetrical  ketones  are  very  high,  not  only  for  ace- 
tic, propionic  and  valeric  acids,  but  also  for  isobutyric,  with  which  an 
experiment  carried  out  at  400-410°  gave  a  70%  yield,  with  caproic, 
heptoic,  nonylic  as  well  as  with  phenyl-acetic.  With  benzoic  acid  at  550° 
a  little  benzophenone  is  formed,  but  chiefly  benzene.™ 

846.  Lithium  Carbonate.    At  550°  this  is  the  most  advantageous 
catalyst  for  transforming  benzoic  acid  into  benzophenone,  always  ac- 
companied by  a  little  anthraquinone;    but   even  in   this,  the  most 
favorable  case,  much  benzene  is  formed.27 

847.  Formation  of  Ketones  in  Liquid  Medium.     In  the  case  of 
monobasic  acids  which  boil  above  300°,  the  ketones  can  be  formed  by 
heating  the  acids  somewhat  above  300°  with  various  catalysts,  includ- 
ing the  oxides  mentioned  above,  silica,  silicates  and  also  finely  divided 
metals.    Stearic  acid  yields  stearone  in  3  hours.27 

II.  Preparation  of  Mixed  Ketones 

848.  A  long  time  ago  Williamson  showed  that  the  calcination  of  a 
mixture   of  the   calcium  salts  of  two  fatty  acids  gave   the   mixed 
ketone:28 

(R.C02)2Ca  +  (R/.C02)2Ca  =  2CaC03  +  2R.CO.R'. 

It  might  be  expected  that  the  catalytic  decomposition  by  means  of 
oxides  when  applied,  not  to  a  single  acid  but  to  a  mixture  of  two  acids, 
would  give  the  mixed  ketone  derived  from  the  two  acids  instead  of  the 
symmetrical  ketone.  Senderens  found  this  to  be  the  case.  We  have: 

R.CO2H  +  R'.CO2H  =  C02  +  H2O  +  R.CO.R'. 

A  simple  method  of  preparing  mixed  ketones  is  to  pass  a  mixture 
of  the  vapors  of  the  two  acids  over  thoria  at  about  400°. 

For  the  success  of  this  method  it  is  sufficient  that  one  of  the  acids 
is  catalyzed  by  thoria:  we  may  use  two  aliphatic  acids  or  one  ali- 
phatic with  benzoic  or  a  toluic  acid,  but  not  benzoic  with  a  toluic. 

26  SABATIER  and  MAILHE,  Compt.  rend.,  158,  830  (1914). 

27  SCHICHT  ACT.  GES.  and  GRUN,  German  patents,  295,657  and  296,677.  —  J . 
Soc.  Chem.  Ind.,  36,  569  and  615  (1917). 

28  WILLIAMSON,  Annalen,  81,  86  (1852). 


305  DECOMPOSITION  OF  ACIDS  851 

The  chief  reaction  is  usually  that  which  furnishes  the  mixed  ke- 
tone,  but  it  is  always  accompanied  by  the  reactions  that  the  two  acids 
would  undergo  separately.  We  obtain  three  ketones  if  we  start  with 
two  aliphatic  acids  or  an  aliphatic  and  phenyl  acetic,  but  only  two 
when  an  aliphatic  acid  is  used  with  benzoic,  a  toluic,  or  a  naphthoic. 

The  separation  of  the  ketones  is  easily  accomplished  by  fractiona- 
tion.  Numerous  mixed  ketones  have  been  prepared  in  this  way. 

849.  The  green  oxide  of  uranium,  though  less  active,  can  replace 
thoria  for  this  preparation:   zirconia  acts  in  the  same  way,  but  does 
not  give  as  good  results  with  the  homologs  of  benzoic  acid.     Lime, 
zinc  oxide,  alumina,  and  chromic  oxide  produce  acetophenone  easily  but 
give  poorer  and  poorer  results  as  the  aliphatic  acid  increases  in  molec- 
ular weight. 

Titania,  stannic  oxide  and  ceria  give  decomposition  products 
chiefly.29 

Cadmium  oxide,  ferrous  and  ferric  oxides,*0  and  calcium  carbonate 
are  excellent  catalysts  for  mixed  ketones.31 

850.  Manganous  oxide  at  400-450°  is  as  good  as  thoria  and  by  its 
use  mixed  ketones  have  been  prepared  from  benzoic  add  with  lauric, 
myristic,  CuK^Ou,  and  stearic,  Ci8H36O2,  as  well  as  phenyl-acetic*2 


CATALYTIC  PREPARATION  OF  ALDEHYDES 

851.  If  in  Williamson's  method  for  preparing  mixed  ketones,  one 
of  the  calcium  salts  is  a  formate,  an  aldehyde  M  is  produced  accom- 
panied by  the  decomposition  products  of  the  individual  salts,  the 
symmetrical  ketone,  R.CO.R,  formaldehyde,  and  methyl  alcohol  as  well 
as  gaseous  products  from  the  formate: 

(R.C02)2Ca  +  (H.C02)2Ca  =  2CaC03  +  2R.CO.H 

aldehyde 

Analogies  would  lead  us  to  expect  that  a  mixture  of  the  vapors  of 
formic  acid  and  another  monobasic  organic  acid  passed  over  an  oxide 
catalyst  would  give  the  aldehyde  corresponding  to  that  acid  according 
to  the  reaction: 

R.C02H  +  H.CO2H  =  R.CO.H  +  CO2  +  H2O. 

89  SENDERENS,  Loc.  cit. 

10  MAILHE,  Compt.  rend.,  157,  219  (1913). 

11  SABATIER  and  MAILHE,  Compt.  rend.,  156,  1732  (1913). 
"  SABATIER  and  MAILHE,  Compt.  rend.,  158,  830  (1914). 

M  LIMPRICHT,  Annalen,  97,  368  (1856).  —  PIRIA,  Ann.  Chim.  Phys.  (3),  48,  113 
(1856). 


852  CATALYSIS  IN  ORGANIC  CHEMISTRY  306 

852.  Sabatier  and  Mailhe  were  able  to  realize  this  reaction  with 
titanic,  as  a  catalyst.    This  constitutes  a  general  method  for  the  prep- 
aration of  aldehydes  from  acids.     It  is  sufficient  to  pass  the  vapors 
of  the  acid  mixed  with  an  excess  for  formic  acid  over  titania  heated 
to  300°.     There  is  evolved  a  mixture  of  carbon  monoxide  resulting 
from  the  decomposition  of  the  formic  acid  by  the  titania  (825)  and 
carbon  dioxide  from  the  desired  reaction.    The  condensate  is  a  mixture 
of  water,  aldehyde,  and  unchanged  acids  from  which  the  aldehyde  is 
easily  separated. 

Aldehydes  derived  from  various  aliphatic  acids  up  to  CQ  have  been 
thus  prepared  with  yields  above  40%  and  reaching  90%. 

Thus  nonylic,  or  pelargonic  acid,  gives  85%  of  nonylic  aldehyde. 
Usually  no  ketone  is  formed;  only  very  small  amounts  of  the  ketones 
are  formed  with  acids  containing  more  than  5  carbon  atoms. 

The  unsaturated  acid,  crotonic,  is  likewise  transformed  into  the 
aldehyde.  The  reaction  gives  poor  results  with  benzole  add  but  works 
well  with  phenyl-acetic,  the  constitution  of  which  is  more  like  the 
aliphatic  acids.  It  gives  a  70%  yield.34 

853.  Manganous  oxide  can  be  substituted  for  titania  and  has  the 
advantages  of  being  readily  prepared  and  of  retaining  its  activity  be- 
cause it  gives  rise  to  less  tarry  deposits.     The  operation  should  be 
conducted  at  a  little  higher  temperature,  300-350°.  The  yields  are  very 
satisfactory,    reaching   50%   with   isovaleric   acid.      Caproic,    heptoic, 
octoic,  and  nonylic  aldehydes  have  been  prepared  in  this  way.35 

854.  The  use  of  thoria  is  less  advantageous  because  it  requires  a 
higher  temperature  and  because  it  favors  the  formation  of  ketones 
which  are  found  with  the  aldehydes;    however,  by  operating  at  270- 
300°,  25  to  30  %,  and  sometimes  more,  of  the  aldehydes  are  obtained.34 


DECOMPOSITION  OF  DIBASIC  ACIDS 

855.  Solid  oxalic  acid,  HOOC.COOH,  mixed  with  alumina  is  de- 
composed below  100°  into  water,  carbon  monoxide  and  dioxide.36 

Glycerine  mixed  with  crystallized  oxalic  acid  produces  a  different 
result:  at  100-110°  carbon  dioxide  and  formic  acid  are  produced: 

HOOC.COOH  =  C02  +  H.C02H. 

When  the  reaction  dies  down  all  that  is  necessary  to  start  it  again 
is  to  add  some  more  oxalic  acid  and  so  on,  the  glycerine  being  able  to 

14  SABATIER  and  MAILHE,  Compt.  rend.,  154,  561  (1912). 
85  SABATIER  and  MAILHE,  Compt.  rend.,  158,  985  (1914). 
"  SENDERENS,  Butt.  Soc.  Chim.  (4),  3,  828  (1908). 


307  DECOMPOSITION  OF  ACIDS  857 

serve  almost  indefinitely,  and  hence  playing  the  part  of  a  catalyst. 
In  reality  there  is  first  the  production  of  a  glycerine  mono-oxalate: 

HOH2C.CH(OH).CH2OH  +  HOOC.COOH  = 
H2O  +  HOH2C .  CH  (OH) .  CH2 .  C02 .  COOH. 

At  100-110°  this  ester  loses  water  and  gives  the  monoformine, 
HOH2C.CH(OH).CH2.CO2H,  which  is  saponified  by  the  water  set 
free  in  the  first  reaction  liberating  formic  acid  and  glycerine  which  is 
thus  free  to  recommence  the  process. 

856.  The  use  of  manganous  oxide  permits  the  preparation  of  cyclo- 
pentanones  from  e-dibasic  fatty  adds. 

The  vapors  of  adipic  acid  carried  along  by  a  current  of  carbon 
dioxide  over  manganous  oxide  at  350°,  give  an  85%  yield  of  cyclo- 
pentanone: 

CH2 .  CH2 .  C02H  CH2 .  CH2\ 

=  C02  +  H20  +  •  /CO. 

CH2 .  CH2 .  C02H  CH2 ,  CH2/ 

Likewise  f3-methyl-cyclopentanone  is  prepared  from  f3-methyl-adipic 
acid.37 

But  with  suberic  acid,  in  which  the  carboxyl  groups  are  separated 
by  6  carbon  atoms,  the  process  gives  only  a  poor  yield  of  suberone  and 
tarry  substances  are  formed  which  gum  up  the  catalyst.38 

CATALYTIC  DECOMPOSITION  OF  ACID  ANHYDRIDES 

857.  The  anhydrides  like  the  acids  can  be  decomposed  catalyt- 
ically  to  form  the  corresponding  symmetrical  ketones,  carbon  dioxide 
only  being  eliminated: 

R.CO.O.CO.R  =  C02  +  R.CO.R. 

Precipitated  calcium  carbonate  gives  good  results  at  450-500°  with 
the  anhydrides  of  acetic,  propionic,  isovaleric,  etc.,  acids.  Thoria  is  also 
suitable  for  this  reaction. 

This  process  gives  a  mixed  ketone  along  with  the  two  symmetrical 
ketones  when  an  acid  and  the  anhydride  of  another  acid  are  used 
together.39 

37  SABATIER  and  MAILHE,  Compt.  rend.,  158,  985  (1914). 
88  GODCHOT  and  TABOURY,  Bull  Soc.  Chim.  (4),  25,  352  (1919). 
39  SABATIER  and  MAILHE,  Bull.  Soc.  Chim.  (4),  13,  320  (1913),  and  Compt.  rend., 
156,  1733  (1913). 


CHAPTER  XIX 
DECOMPOSITION  OF  ESTERS  OF  ORGANIC  ACIDS 

§  i.  — ESTERS  OF  MONOBASIC  ACIDS 

858.  IN  the  absence  of  catalysts  the  esters  of  monobasic  acids  are 
difficult  to  decompose  by  simply  heating;    the  decomposition  is  slow 
and  such  high  temperatures  are  required  that  the  molecules  are  broken 
up.    We  may  mention  that  ethyl  benzoate  heated  in  a  sealed  tube  above 
300°  is  slowly  decomposed  into  benzoic  acid  and  ethylene.     Colson, 
who  noted  this  reaction  and  a  similar  decomposition  of  ethyl  stearate, 
considered  this  tendency  to  decompose  into  the  acid  and  an  unsatu- 
rated  hydrocarbon  a  general  property  of  esters.1 

The  presence  of  a  catalyst  acting  at  the  same  time  on  the  alcohols 
end  on  the  acids  should  greatly  facilitate  the  decomposition  of  esters 
which  should  yield,  in  conformity  with  what  has  been  said  above,  the 
unsaturated  hydrocarbon  and  the  decomposition  products  of  the  acid, 
water,  carbon  dioxide,  and  the  symmetrical  ketone.  Some  observa- 
tions relative  to  the  action  of  alumina  on  ethyl  acetate,  propionate 
and  butyrate  confirmed  this  prediction,  but  on  the  contrary,  these 
same  esters  gave  with  thoria  a  complicated  decomposition  which  has 
not  been  cleared  up.2 

Sabatier  and  Mailhe  have  studied  a  great  number  of  cases  of  the 
action  of  various  catalytic  oxides  on  esters  of  various  sorts  and  have 
indicated  the  general  conditions  that  govern  the  decomposition.3 

Formic  esters  require  separate  treatment  and  will  be  taken  up 
after  the  other  esters. 

859.  If  an  ester  derived  from  a  primary  aliphatic  alcohol  and  from 
a  monobasic  organic  acid,  other  than  formic,  be  brought  in  contact 
with  a  catalytic  oxide,  MO,  derived  from  an  amphoteric  hydroxide, 
M(OH)2,  the  following  reaction  will  take  place: 

2R.CQ.OCnH2n+i  +  2MO  =  (R.COO)2M  +  (CnHn2+iO)2M. 

ester 

The  salt,  (RCO.O)2M,  and  the  alcohol  derivative,  (CnH2n+iO)2M 
are  both  unstable,  if  the  oxide  chosen  is  at  the  same  time  a  catalyst 

1  COLSON,  Compt.  rend.,  147,  1054  (1908). 

2  SENDERENS,  Bull.  Soc.  Chim.  (4),  5,  482  (1909). 

3  SABATIER  and  MAILHE,  Compt.  rend.,  152,  669  (1912),  and  154,  49  and  175 
(1912). 

308 


309        DECOMPOSITION  OF  ESTERS  OF  ORGANIC  ACIDS       861 

for  the  decomposition  of  alcohols  and  of  acids  at  the  operating  tem- 
perature. 

860.  First  Case.  If  the  instability  of  the  two  temporary  com- 
pounds is  of  the  same  order  they  will  decompose  simultaneously  and 
the  decomposition  becomes: 

(R.CO.R  +  C021 

(1)      2R  .  CO  .  OCnH2n+i  +  2MO  =  \     ketone  I  +  2MO. 

2CnH2n 


hydrocarbon 

A  symmetrical  ketone  is  produced  and  an  unsaturated  hydrocarbon 
which,  if  it  is  a  gas  (ethylene,  propylene  and  butylene)  has  twice  the 
volume  of  the  carbon  dioxide  produced.  This  was  the  case  in  the 
experiments  with  alumina  mentioned  above  (858). 

If  the  ester  is  a  methyl  ester  there  is  no  separation  of  water,  and 
methyl  ether,  (CH3)2O,  is  formed. 

861.  Second  Case.  If  the  catalyst  is  more  active  toward  acids 
than  with  alcohols,  the  decomposition  of  the  complex,  (R.CO.O)2M, 
is  more  rapid  than  that  of  the  alcohol  compound.  The  water  formed 
in  reaction  (1)  has  time  to  react  with  an  equivalent  amount  of  the 
latter  and  decomposes  it  to  regenerate  the  alcohol: 

,  +  H20  =  MO  +  2CnH2n+1.OH. 


alcohol 

This  combined  with  the  former  reaction  gives: 
(2)  4R.CO.OCnH2n+l  =  2R.CO.R+2C024-2CnH2n+2CnH2n+1.OH. 

ketone 

There  is  the  simultaneous  formation  of  ketone  and  alcohol  and  of 
equal  volumes  of  carbon  dioxide  and  of  unsaturated  hydrocarbon  (if 
it  is  a  gas).  This  is  usually  the  case  with  decompositions  caused  by 
thoria,  e.g.  at  310°  with  ethyl  acetate,  propyl  acetate,  propyl  propionate, 
isobutyl  acetate,  and  ethyl  caproate.* 

4  Titania  prepared  by  the  precipitation  of  the  hydroxide  from  the  sulphate  cata- 
lyzes the  decomposition  of  ethyl  acetate  two  thirds  according  to  the  equation: 

(1)  CH3C02C2H6  .  CA  +  CHsCOOH 
and  one  third  according  to: 

(2)  2CH3CO2C2H6  -  CH3COCH,  +  CO2  +  C2H4  +  H2O 

Titania  prepared  by  precipitating  blue  titanous  hydroxide  from  a  solution  of 
titanous  chloride,  and  then  allowing  this  to  oxidise  to  the  white  titanic  hydroxide 
while  suspended  in  the  solution,  catalyzed  the  reaction  one  third  according  to  (1) 
and  two  thirds  according  to  (2). 

Thoria  prepared  by  ignition  of  the  nitrate  gives  very  little  ethylene,  as  was 
found  by  Sabatier,  but  thoria  prepared  by  precipitation  of  the  hydroxide  gives 
almost  as  much  ethylene  as  would  be  called  for  by  (2). 

Alumina  does  not  only  give  reaction  (2)  but  a  fifth  to  two  thirds  of  the  ethyl 
acetate  is  decomposed  according  to  (1).  The  method  of  preparation  of  the  cata- 
lyst and  the  length  of  time  it  has  been  used  determine  the  proportions.  — 
Homer  Adkins. 


862  CATALYSIS  IN  ORGANIC  CHEMISTRY  310 

862.  Elevation  of  temperature  accelerates  the  decomposition  of 
the  unstable  intermediates  and  tends  to  bring  the  reaction  nearer  to 
(1).    This  is  the  case  with  isobutyl  acetate  over  thoria  at  above  350° 
and  for  ethyl  caproate  at  about  360°.    Besides  when  the  temperature 
becomes  high,  the  alcohols  suffer  more  or  less  decomposition  into  hy- 
drogen and  aldehydes,  easy  to  recognize,  and  these  may  be  partially 
split  up  into  hydrocarbons  and  carbon  monoxide. 

863.  Third  Case.     If  the  catalyst  is  less  active  with  acids  than 
with  alcohols,  the  temporary  complex,   (R.CO.O)2M,  will  be  decom- 
posed only  slowly.    The  water  set  free  by  the  rapid  decomposition  of 
the  alcohol  complex  will  act  on  the  above  to  set  the  acid  free: 

(R.CO.O)2M  +  H20  =  MO  +  2R.CO.OH. 

acid 

In  this  case  the  formation  of  ketone  and  liberation  of  carbon  di- 
oxide are  less  important :  the  production  of  unsaturated  hydrocarbon 
and  setting  free  of  acid  predominate. 

This  is  what  takes  place  over  titania  with  esters  of  acetic,  propi- 
onic,  butyric  and  valeric  acids,  which  acids  it  decomposes  more  slowly 
than  it  does  the  alcohols. 

864.  Fourth  Case.     The  exaggeration  of  the  preceding  case  is 
found  with  those  catalysts  which  are  active  with  alcohols  but  are  in- 
capable of  decomposing  acids.    This  is  the  case  with  various  catalytic 
oxides,  e.g.  thoria  and  titania  with  esters  of  benzoic  and  toluic  acids, 
and  with  boric  anhydride  with  esters  of  aliphatic  acids,  since  boric  acid 
can  form  the  temporary  complexes  with  the  alcohols  only.     In  such 
cases  we  may  write  the  reaction  as  follows: 

2R.CO.OCnH2n+1  +  MO  =  M(OCnH2n+i)2  +  (R.CO)2Q 

anhydride 

=  MO  +  2CnH2n  +  H20  +  (R.CO)20 
=  MO  +  2CnH2n  +  2R.C02H. 

acid 

There  will  be  a  total  regeneration  of  the  acid  with  the  formation 
of  the  unsaturated  hydrocarbon  exclusively.  It  has  been  found  that 
ethyl  benzoate  is  decomposed  into  benzoic  acid  and  ethylene  by  thoria 
above  400°,  as  in  Colson's  sealed  tube. 

Likewise  ethyl  valerate  catalyzed  by  boric  anhydride  above  400°, 
gives  ethylene  and  valeric  acid  exclusively. 

865.  Methyl  esters  which  can  give  only  methyl  ether  are  difficult 
to  decompose  :    the  reaction,  which  requires  a  higher  temperature, 
yields  exclusively  carbon  dioxide,  methyl  ether  and  the  ketone,  fre- 
quently partially  decomposed,  and  resulting  water  which  may  saponify 
a  part  of  the  ester  to  form  free  acid  and  methyl  alcohol. 


311        DECOMPOSITION  OF  ESTERS  OF  ORGANIC  ACIDS       868 

Catalytic  Decomposition  of  Formic  Esters 

866.  In  the  absence  of   catalysts,   formic  esters  are  quite  stable " 
when  the  vapors  of  ethyl  formate  are  passed  through  a  glass  tube  at 
400°,  no  appreciable  decomposition  is  observed,  but  the  decomposition 
is  very  rapid  in  contact  with  catalysts  that  decompose  formic  acid 
(821),  and  takes  place  at  temperatures  lower  than  those  required  for 
the  esters  of  other  aliphatic  acids,  but  higher  than  those  required  by 
formic  acid. 

Sabatier  and  Mailhe  have  shown  that  this  decomposition  takes 
place  according  to  two  different  reactions  at  the  same  time,  the  one 
similar  to  the  usual  decomposition  of  esters  of  other  aliphatic  acids: 

(1)  2H  .CO2CnH2n41  =  H.CO.H  +  CO2  +  (CnH2n+])2O 

formaldehyde  ether 

the  ether  surviving  only  in  the  case  of  methyl  ether,  splitting  in  other 
cases  into  water  and  unsaturated  hydrocarbon  (H2O  +  2CnH2n) ;  the 
other  always  predominating,  is  peculiar  to  formic  esters: 

(2)  H.C02CnH2n+1  =  CO  +  CnH2n+1.OH. 

alcohol 

A  portion  of  this  alcohol  is  decomposed  at  the  reaction  tempera- 
ture, either  into  aldehyde  and  hydrogen  (with  metals  or  manganous 
oxide),  or  into  unsaturated  hydrocarbon  and  water  (with  thoria  and 
alumina),  or  in  both  ways  (with  mixed  catalysts).  The  water  result- 
ing from  reaction  (1)  or  from  the  dehydration  of  the  alcohol  formed 
according  to  equation  (2)  can  saponify  a  part  of  the  ester  to  alcohol 
and  free  formic  acid  which  is  then  decomposed  in  the  way  already 
described  (821). 5 

867.  Metals.    Finely  divided  metals  can  easily  cause  the  decom- 
position of  formic  esters,  nickel  above  220°,  platinum  above  270°,  and 
copper  above  350°.    Reaction  (2)  greatly  predominates  and  gives  the 
alcohol  which  the  metal  breaks  down  to  aldehyde,  along  with  the  car- 
bon monoxide.    With  copper  or  with  nickel  at  a  low  temperature 
the  aldehyde  survives,  but  with  platinum  or  with  nickel  at  a  high 
temperature  (618)  it  is  largely  destroyed. 

868.  Titania.    Reaction  (2)  takes  place  almost  exclusively.    From 
methyl  formate,  methyl  alcohol  and  methyl  ether  resulting  from  its 
partial  dehydration  are  obtained.     The  gas  collected  over  water  is 
practically  pure  carbon  monoxide  without  the  dioxide  because  the  for- 
mic acid,  under  these  conditions,  gives  only  carbon  monoxide  and 
water   (825). 

8  SABATIER  and  MAILHE,  Compt.  rend.,  154,  49  (1912). 


869  CATALYSIS  IN  ORGANIC  CHEMISTRY  312 

869.  Zinc  Oxide.    It  is  again  reaction  (2)  that  predominates,  but 
the  formic  acid  that  is  set  free  by  the  water  resulting  from  the  dehy- 
dration of  the  alcohol,  is  decomposed  by  the  catalyst  into  water  and 
carbon  dioxide  which  is  found  mixed  with  the  monoxide. 

870.  Thoria.     Reaction  (2)  predominates  but  is  accompanied  by  (1) 
which  furnishes  a  certain  amount  of  formaldehyde  which  is  diminished 
as  the  reaction  temperature  is  raised. 

§  2  —  DECOMPOSITION  OF  ESTERS  IN  THE 
PRESENCE  OF  AMMONIA 

871.  When  the  vapors  of  an  ester  of  an  organic  monobasic  acid 
mixed  with  ammonia  are  passed  over  thoria   or  alumina  at   about 
480-90°,  nitriles  are  obtained  by  the  elimination  of  water  and  alcohol 
or  of  decomposition  products  of  the  alcohol. 

Methyl  esters  give  the  alcohol,  partially  split  into  methyl  ether  and 
water  or  into  formaldehyde  and  hydrogen. 

Esters  of  other  aliphatic  alcohols  give  the  unsaturated  hydrocarbons, 
while  phenol  esters  yield  phenol  the  major  portion  of  which  remains: 

R.CO.OR'  +  NH3  =  H20  +  R'OH  +  RON. 

Ethyl  acetate  gives  ethylene  and  acotonitrile  and  isoamyl  acetate  yields 
amylene  and  acetonitrik,  while  phenyl  acetate  liberates  the  same  nitrile 
and  phenol. 

Analogous  results  have  been  obtained  with  esters  of  propionic,  bu- 
tyric, isovakric,  nonylic  and  caproic  adds. 

Methyl  benzoate  gives  more  than  80%  of  benzonitrile  with  methyl 
alcohol  and  formaldehyde.  Ethyl  and  isopropyl  benzoates  yield  the 
same  nitrile.  The  esters  of  the  three  toluic  acids  behave  in  the  same 
way. 

Ethyl  a-  and  /3-naphthoates  are  almost  quantitatively  transformed 
into  the  a-  and  /3-naphthonitriles. 

Ethyl  phenyl-acetate  gives  an  excellent  yield  of  benzyl  cyanide.6 

§  3.  —  ESTERS  OF  DIBASIC  ACIDS 

872.  The  catalytic  decomposition  of  esters  of  dibasic  acids  has 
been  as  yet  very  incompletely  studied. 

Catalytic  oxides  such  as  alumina  and  thoria  cause  decompositions 
readily.  If  we  extend  to  the  esters  of  dibasic  acids  the  interpretation 
above  set  forth  for  the  action  of  these  oxides,  we  can  predict  that  an 
oxide,  MO,  will  effect  the  reaction: 

•  MAILHE,  Bull  Soc.  Chim.  (4),  23,  232  (1918). 


313        DECOMPOSITION  OF  ESTERS  OF  ORGANIC  ACIDS       873 

/CO.  OR  /CO.Ov  /OR 

(CH2)X(  +  2MO  =  (CH2)X(  )M  +  M( 

\CO.OR  \CO.O/  \OR 

ester  metal  salt  alcoholate 

If  the  oxide  is  at  the  same  time  a  catalyst  for  acids  and  for  alco- 
hols, the  compounds  thus  formed  will  be  unstable  and  will  decompose 
as  follows: 

/CO.Ov  XXX 

(CH2)X(  )M  =  MO  +  (CH2)X(        >o 

\co.o/  \co/ 


anhydride 

/OR  R\ 

and:  M(          =  MO  +       )O. 

\OR  R/ 

ether 

The  oxide,  MO,  is  entirely  regenerated  and  can  carry  on  the  reaction 
indefinitely.  We  will  obtain  as  results  of  the  catalysis,  the  acid  anhy- 
dride, or  its  debris,  if  it  is  unstable,  the  ether,  or  in  most  cases,  the 
catalytic  decomposition  products  of  that  ether,  i.e.  water  and  an 
unsaturated  hydrocarbon. 

873.  These  predictions  have  been  verified  by  Sabatier  and  Mailhe 
in  the  case  of  the  neutral  esters  of  oxalic,  malonic  and  succinic  acids 
over  thoria.7 

C0\ 

Oxalic  anhydride,      •       X),    is  unknown  and  the  mixture,  CO2  + 
CO/ 

XXX 

CO,  is  obtained  in  its  place.     Malonic  anhydride,  CBk  X),    is 

equally  unstable  and  decomposes  into  carbon  suboxide,  CO  :  C  :  CO, 
which  polymerizes  into  reddish  products  or  decomposes  into  carbon 
monoxide,  dioxide  and  carbon. 

Succinic  anhydride  is  stable  it  the  temperature  is  not  too  high  and 
can  be  collected  as  crystals  melting  at  177°.  If  the  temperature  is 
above  350°,  it  is  decomposed  into  carbon  monoxide  and  dioxide,  ethyl- 
ene  and  condensation  products. 

These  results  have  been  verified  for  the  ethyl,  propyl,  isobutyl  and 
isoamyl  esters  of  the  three  acids  :  except  in  the  case  of  the  ethyl 
esters,  where  the  stable  ethyl  ether  can  be  collected,  the  debris  of  the 
esters,  water  and  the  unsaturated  hydrocarbon,  are  found.8 

7  SABATIER  and  MAILHE,  Bull.  Soc.  Chim.  (4),  n,  369  (1912). 

8  SABATIER  and  MAILHE,  Loc.  dt.  and  unpublished  results. 


874  CATALYSIS  IN  ORGANIC   CHEMISTRY  314 

With  esters  of  oxalic  add,  the  catalytic  decomposition  begins  at 
very  moderate  temperatures  and  is  already  rapid  at  220°:  higher  tem- 
peratures are  required  for  malonates  and  still  higher  for  succinates. 

A  decomposition  of  this  nature  has  been  found  in  the  particular 
case  of  ethyl  oxalate  over  alumina:  at  200°,  ethyl  ether,  carbon  mon- 
oxide and  dioxide  are  obtained,  while  at  360°,  the  ethyl  ether  is  re- 
placed by  ethylene.9 

874.  The  catalytic  decomposition  of  ethyl  succinate  over  alumina 
at  400°,  according  to  Senderens,  liberated  ethylene  and  carbon  dioxide 
and  produced  p.  cyclohexadione.10  But  Sabatier  and  Mailhe  were  not 
able  to  verify  this  and  obtained  only  succinic  anhydride  along  with 
ethylene  and  carbon  dioxide.  The  same  results  were  obtained  with 
alumina  at  260°. 

Ethyl  glutarate  over  alumina  at  270°,  gave  only  ethylene  and  glu- 
taric  add.  Ethyl  adipate  furnished  ethylene  and  adipic  add  at  300°. ll 
At  higher  temperatures  this  should  have  given  cyclopentanone  (856). 

•  SENDERENS,  Bull  Soc.  Chim.  (4),  3,  826  (1908). 
"  SENDERENS,  Bull.  Soc.  Chim.  (4),  5,  485  (1909). 
11  MICHIELS,  Bull.  Soc.  Chim.  Beige,  27,  227  (1913);  C.  A.,  8,  1106  (1914). 


CHAPTER  XX 

ELIMINATION  OF  HYDROGEN  HALIDES   OR  SIMILAR 

MOLECULES 

875.  THE  elimination  of  hydrogen  halides  can  take  place  from  a 
single  molecule  or  by  condensation  from  two  molecules.  Anhydrous 
chlorides  are  the  chief  catalysts  in  both  cases. 


§  i.  —  ELIMINATION  OF  HYDROGEN  HALIDE    FROM 
A  SINGLE  MOLECULE 

876.  When  an  alkyl  mono-chloride  is  passed  over  a  layer  of  various 
anhydrous  metal  chlorides  in  a  tube  maintained  at  above  260°  there  is 
rapid  decomposition  into  unsaturated  hydrocarbon  and  hydrochloric 
acid: 

CnH.2n+lCl   =   HC1  -f-  CnHiJn' 

Methyl  chloride  alone  does  not  decompose  in  this  way. 

Barium,  nickel,  cobalt,  lead,  cadmium  and  ferrous  chlorides  are  suit- 
able for  effecting  this  reaction.  Primary  chlorides  are  decomposed 
above  260°  and  rapidly  at  300°  while  secondary  and  tertiary  are  still 
more  easily  acted  on. 

The  same  metal  chlorides  decompose  alkyl  mono-bromides  or  mono- 
iodides  in  the  same  way  to  form  hydrobromic  or  hydroiodic  acids,  but 
higher  temperatures  are  required.1 

The  recombination  of  the  unsaturated  hydrocarbon  with  the  lib- 
erated hydrogen  halide  takes  place  to  a  certain  extent  in  the  tube 
beyond  the  catalytic  chloride  and  may  yield  a  certain  amount  of 
secondary  or  tertiary  isomers  of  the  original  alkyl  halide. 

Dry  barium  chloride  gives  very  good  results  and  can  effect  this 
decomposition  indefinitely;  if  it  is  dissolved  in  water  after  long  use, 
there  is  a  small  residue  of  viscous  very  condensed  hydrocarbons  with 
a  petroleum  odor. 

The  chlorides  of  monovalent  metals,  silver,  sodium,  and  potassium 
are  inactive. 

The  process  applies  to  monochlor  derivatives  of  cyclohexane  and 
cyclopentane.  It  can  succeed  with  unsaturated  mono-chlorides  and  even 

1  SABATIER  and  MAILHE,  CompL  rend.,  141,  238  (1905). 

315 


877  CATALYSIS  IN  ORGANIC  CHEMISTRY  316 

with  halogenated  alcohols  2  as  well  as  with  dichlorcyclohexane  which  is 
converted  to  dihydrobenzene.3 

877.  Anhydrous  aluminum  chloride  acts  actively  in  the  same  man- 
ner, but  it  has  the  disadvantage  of  producing  liquid  products  that 
hinder  the  continuation  of  the  catalysis.     It  has  been  used  to  trans- 
form propyl  chloride  into  propylene.* 

878.  The  catalysis  can  be  explained  by  the  assumption  of  an  un- 
stable organo-metallic  combination  derived  from  the  alkyl  chloride: 

CnH2+n+i.Cl  +  BaCl2  =  HC1  +  Cl.Ba.CnH2n.Cl. 

The  mixed  complex  thus  formed  would  decompose  rapidly  to  give 
the  unsaturated  hydrocarbon: 

Cl.Ba.CnH2n.Cl  =  BaCl2  +  C2H2n. 

The  regenerated  chloride  can  repeat  the  cycle  of  reactions  indefi- 
nitely. The  formation  of  such  a  mixed  complex  can  be  observed  in  the 
case  of  anhydrous  aluminum  chloride:  mixed  with  isobutyl  chloride 
at  -10°,  no  reaction  takes  place  but  if  the  mixture  is  warmed  to  0°, 
hydrogen  chloride  and  isobutylene  are  evolved  and  an  intensely 
colored  liquid  is  formed. 

At  300°,  ferric  chloride  causes  the  elimination  of  hydrogen  chloride, 
but  no  isobutylene  is  formed;  a  solid  of  high  molecular  weight  is 
produced. 

Chromic  chloride,  CrCla,  does  not  act.6 

879.  As  has  been  mentioned  above  (876),  this  kind  of  catalysis  can 
be  applied  to  poly-halogen  derivatives. 

Heptachlorpropane,  CC13  .  CC12  .  CHC12,  is  decomposed  above  250° 
by  cuprous  chloride  with  the  elimination  of  hydrogen  chloride  to  give 
pentachlor-propylene,  CCls  .  CC1  :  CC12  at  the  same  time  that  a  split- 
ting of  the  molecule  yields  chloroform  and  tetrachlorethylene,  C2Cl4. 
Zinc  and  barium  chlorides  have  little  action.6  Aluminum  chloride  gives 
a  reaction  which  is  limited  by  the  reverse  combination  of  the  chloro- 
form with  the  tetrachlorethylene  (902). 

880.  Benzyl  chloride  is  easily  decomposed  by  various   anhydrous 
chlorides  particularly  those  of  barium  and  nickel,  into  hydrochloric 
acid  and  a  very  high  molecular  weight  compound  of  the  empyrical 
formula  CyH^,  previously  discovered  by  Cannizzaro  and  identical  with 


8  BADISCHB,  German  patent,  255,519  (1913). 
»  BADISCHE,  French  patent,  441,203. 
4  KEREZ,  Annalen,  231,  306  (1885). 
6  SABATIER  and  MAILHE,  Compt.  rend.,  141,  238  (1905). 

•  BOESEKEN,  VAN  DEB  ScHEER  and  BE  VOGT,  Rec.  Trav.  Chim.  Pays-Bas,  34, 
78  (1915). 


317  ELIMINATION  OF  HYDROGEN  HALIDES  884 

that  formed  by  the  dehydration  of  benzyl  alcohol  (714) 7  and  which 
is   perhaps   hexaphenyl-cyclohexane,    (C6H5.CH)6.     The  reaction  is: 

x(C6H5.CH2Cl)  =  xHCl  +  (C6H5.CH)X. 

881.  Anhydrous  metallic  oxides  can  likewise  effect  the  decomposi- 
tion of  alkyl  halides  in  consequence  of  the  formation  of  a  certain 
amount  of  the  corresponding  chloride.     When  isobutyl  chloride  is 
passed  over  alumina  at  above  250°,  the  slight  dissociation  of  the  alkyl 
chloride  at  that  temperature  can  account  for  the  formation  of  a  little 
chloride  or  oxy-chloride  of  aluminum  which  starts  the  catalytic  action 
and  the  amount  of  which  increases  rapidly  in  consequence  of  the  hyd- 
rochloric  acid  evolved.     This  is  the  explanation  of  the  decomposi- 
tions of   alkyl    chlorides  with    alumina  that    have  been  described.8 
Thoria  above  390°  has  been  proposed  for  the  decomposition  of  tetra- 
chlor ethane  into  trichlorethylene:   there  is  the  simultaneous  formation 
of  carbon  hexachloride,  Cede.9 

882.  It  is  probably  the  formation  of  nickel  chloride  also,  to  which 
may  be  attributed  the  identical  catalytic  effect  of  reduced  nickel  on 
alkyl  chlorides  in  the  presence  of  hydrogen;   the  decomposition  takes 
place  easily  above  250°. 10 

§  2.  —  CONDENSATIONS   EFFECTED   BETWEEN   MOLECULES 
WITH  ELIMINATION   OF  HYDROGEN  HALIDE 

883.  Anhydrous  aluminum  chloride  causes  condensation  with  elim- 
ination of  hydrochloric  acid  between  aromatic  hydrocarbons  and  various 
alkyl  or  cyclo-alkyl  chlorides  and  bromides  effecting  the  synthesis  of  a 
large  number  of  aromatic  compounds.    This  is  the  basis  of  the  Friedel 
and  Crafts  synthesis.11 

I.  Alkylation  of  Aromatic  Hydrocarbons 

884.  Method  of  Operating.    It  is  common  to  use  a  large  well  dried 
flask  with  a  stopper  through  which  passes  a  very  large  tube  the  upper 
end  of  which  is  closed  by  a  stopper  and  which  permits  the  introduc- 
tion of  the  solid  aluminum  chloride  and  on  the  side  of  which  is  fused 
a  tube  inclined  upward  and  connected  with  a  reflux  condenser.    The 
hydrogen  chloride  which  is  evolved  escapes  at  the  top  of  this  con- 

7  CANNIZZAKO,  Annalen,  92,  114  (1854). 

8  SENDERENS,  Bull.  Soc.  Chim.  (4),  3,  823  (1908). 

9  CHEM.  FABR.  BUCKATJ,  German  patent,  274,782,  J.  Soc.  Chem.  Ind.t  33,  807 
(1914). 

10  SABATIER  and  MAILHE,  Compt.  rend.,  138,  407  (1904). 

11  FRIEDEL  and  CRAFTS,  Ann.  Chim.  Phys.  (6),  i,  489  (1884). 


885  CATALYSIS  IN  ORGANIC  CHEMISTRY  318 

denser  and  may  be  led  into  a  tarred  flask  of  water,  the  gain  in  weight 
of  which  serves  as  a  means  of  following  the  reaction  so  that  it  may  be 
stopped  when  the  theoretical  amount  of  this  acid  has  been  liberated. 

The  aromatic  hydrocarbon  in  large  excess  (usually  10  times  the 
calculated  amount)  is  mixed  with  the  halogen  compound  with  which  it 
is  to  react  and  put  into  the  flask  which  is  warmed  on  the  water  bath. 
The  well  pulverized  anhydrous  aluminum  chloride  is  added  in  small 
portions,  2  to  20  g.  at  a  time.  Whenever  the  evolution  of  hydrogen 
chloride  dies  down  a  fresh  portion  of  the  chloride  is  added. 

If  the  alkyl  halide  is  a  gas  (methyl  or  ethyl  chloride),  it  may  be 
passed  into  the  flask  after  the  addition  of  a  certain  amount  of  alu- 
minum chloride. 

When  the  reaction  is  considered  finished,  the  flask  is  cooled  and 
the  mixture  is  poured  into  a  large  excess  of  cold  water  acidulated  with 
hydrochloric  acid;  the  oily  layer  is  separated,  washed  and  dried  and 
fractionated. 

The  simplest  case  is  methyl  chloride  with  benzene: 

C6H6  +  CH3C1  =  HC1  +  C6H5.CH3. 

toluene 

885.  Often  excellent  yields  are  obtained  but  the  chief  product  is 
always   accompanied    by  others,  particularly  the  di-  and    tri-  sub- 
stituted, resulting  from  the  reaction  of  the  first  product  with  a  second 
molecule  of  the  halide.     Thus  in  the  simplest  case,  that  of  methyl 
chloride  on  benzene,  the  latter  reacts  with  the  toluene  that  is  formed 
to  give  a  mixture  of  the  xylenes.    These  can  react  in  their  turn  to  yield 
trimethyl-benzenes  (1,  2,  4  and  1,  3,  5)  and  if  the  reaction  is  prolonged, 
tetramethyl-benzene(l,  2,  4,  5),  then    pentamethyl-  and    finally    hexa- 
methyl-benzene  are  formed. 

By  stopping  the  reaction  when  the  calculated  amount  of  acid  has 
been  evolved  these  complications  are  avoided  for  the  most  part. 

The  yield  of  monosubstituted  hydrocarbon  is  considerably  in- 
creased when  an  amount  of  aluminum  chloride  equal  to  15  or  20  %  of 
the  weight  of  the  alkyl  chloride  is  used. 

The  use  of  carbon  disulphide  as  a  solvent  sometimes  facilitates  the 
reaction.12 

Alkyl  chlorides,  bromides  or  iodides  may  be  used  interchangeably, 
the  latter  evolving  hydrogen  bromide  and  iodide. 

886.  In  place  of  using  aluminum  chloride  as  above  described,  the 
flask  may  be  filled  with  aluminum  turnings   (previously  cleaned  by 
boiling  with  alcohol  and  washing  with  ether)  and  a  current  of  dry  hydro- 

12  ANSCHUTZ,  Annakn,  235,  207  (1886). 


319  ELIMINATION  OF  HYDROGEN  HALIDES  889 

gen  chloride  passed.13      Aluminum  turnings  may  be  used  with  mercuric 
chloride  which  attacks  the  metal  rapidly  forming  the  chloride  14 

In  some  cases  the  aluminum  chloride  is  put  in  the  flask  first  and 
covered  with  carbon  disulphide  and  then  the  mixture  of  the  two  sub- 
stances that  are  to  react  is  run  in. 

887.  Reversal  of  the  Reaction.    The  addition  of  alkyl  groups  may 
be  limited  by  the  reverse  reaction  of  removing  them,  and  this  is  also 
catalyzed  by  aluminum  chloride. 

When  the  poly-alkyi  benzenes  are  treated  with  aluminum  chloride  and 
a  current  of  hydrogen  chloride,  the  alkyl  side  chains  are  eliminated  as 
alkyl  chlorides. 15  From  hexamethyl-benzene  we  may  pass  to  pentamethyl-, 
to  tetramethyl-  (1,  3,  4,  6)  and  (1,  3,  4,  5)  to  trimethyl-  (1,  3,  4)  and 
(1,  3,  5)  to  meta  and  para  xylenes,  then  toluene  and  finally  benzene.18 

888.  It  may  happen  that  side  chains  are  taken  off  of  one  molecule 
and  put  on  another  in  consequence  of  splitting  off  an  alkyl  halide 
which  then  reacts  with  the  other  molecule. 

Thus  poly-ethyl-benzenes  in  presence  of  benzene  and  aluminum  chlo- 
ride, retrograde  towards  ethyl-benzene,  particularly  in  a  current  of 
hydrogen  chloride  which  carries  off  the  ethyl  chloride.17 

Ethyl-benzene  kept  in  contact  with  aluminum  chloride  furnishes 
simultaneously  benzene  and  diethyl-benzene.  Isomerizations  may  result 
from  an  alkyl  group  being  taken  off  and  put  on  again.  From  p.xylene 
we  may  get  m.xylene  and  inversely;  pseudocumene  (1,  3,  4  -  tri-methyl- 
benzene)  may  give  mesitylene(l,  3,  5).18 

889.  Results   Obtained.     The   reaction   goes   well   with   various 
aromatic  hydrocarbons,   benzene  and  its  homologs  as  well  as  with 
naphthalene  19  and  diphenyl.     The  homologs  of  benzene  frequently 
give  better  results  than  benzene  itself. 

It  was  developed  first  for  alkyl  mono-chlorides  but  may  go  equally 
well  with  cyclohexyl  monochlorides:  cyclohexyl  chloride  and  benzene 
give  phenyl-cyclohexane.20 

13  STOCKHAUSEN  and  GATTERMANN,  Berichte,  25,  3521  (1891). 

14  RADZIEWANOWSKI,  Berichte,  28,  1135  (1895). 
16  JACOBSEN,  Berichte,  18,  339  (1885). 

16  This  reaction  has  been  extensively  used  for  the  manufacture  of  toluene  from 
the  xylenes.  —  E.  E.  R. 

17  RADZIEWANOWSKI,  Berichte,  27,  3235  (1894).  —  BOEDTKER  and  HALSE,  Bull. 
Soc.  Chim.  (4),  19,  444  (1916). 

18  ANSCHUTZ  and  IMMENDORF,  Berichte,  17,  2816  (1884),  and  18,  657  (1885). 

19  It  is  remarkable  that  when  a  solution  of  naphthalene  in  benzene  is  treated 
with  phthalic  anhydride  in  the  presence  of  aluminum  chloride,  the  naphthalene 
reacts  to  the  exclusion  of  the  benzene.  —  HELLER  and  SCH#LKE,  Berichte,  41,  3627 
(1908).  — E.  E.  R. 

20  KOURSANOF,  J.  Russian  Phys.  Chem.  Soc.,  33,  527  (1901);  Bull.  Soc.  Chim. 
(3),  28,  271  (1902). 


890  CATALYSIS  IN  ORGANIC  CHEMISTRY  320 

It  is  also  applicable  to  the  chlormethyl  ethers,  R.O.CH2C1,  which 
form  the  ether  R.O.CH^R'  with  an  aromatic  hydrocarbon,  R'H. 
With  benzene  the  reaction  goes  regularly  in  the  cold  but  the  yield  is 
only  30%,  because  benzyl  chloride  is  also  formed  by  a  side  reaction 
which  liberates  the  alcohol,  R.OH  (818) .21 

The  reaction  applies  to  derivatives  of  aromatic  hydrocarbons  which 
are  chlorinated  in  a  side  chain,  e.g.  benzyl  chloride,  C6H5 .  CH2C1.22 

Unsaturated  monochlorides  or  monobromides  may  be  used.  Thus 
vinyl  bromide,  CH*:  CHBr,  condenses  with  benzene  to  form  styrene.23 

890.  Dihalogen  derivatives  may  also  be  used.     Ethylene  chloride 
reacts  with  benzene  to  form  sjTnmetrical  diphenyl-ethane 24  and  1,  1- 
dibrom-ethylene  forms  1,  1-diphenyl-ethylene,  CH2 :  C  (C6H6)2.25 

Ethylidene  chloride,  CHs.CHCl2,  gives  similarly  1,  1 -diphenyl- 
ethane,  CHa .  CH  (CeH5)2,  but  the  reaction  may  be  complicated  by  the 
formation  of  ethyl-benzene  and  dihydro-dimethyl-anthracene.™ 

Benzol  chloride,  CeH^.CHC^,  with  5  parts  of  benzene  and  a  little 
aluminum  chloride,  yields  triphenyl-methane,27  which  may  also  be 
formed  from  benzene  and  chloroform,  CHCls.28 

II.   Synthesis  of  Ketones 

891.  The  Friedel  and  Crafts  reaction  is  still  more  easily  applied  to 
the  production  of  ketones,  by  the  reaction  of  aromatic  hydrocarbons  with 
carbonyl  chloride,  or  with  the  chlorides  of  aliphatic  or  aromatic  acids. 

Thus  carbonyl  chloride  and  benzene  form  benzophenone: 

COC12  +  2C6H6  -  2HC1  +  C6H5.CO.C6H5. 
Acetyl  chloride  produces  acetophenone  from  benzene : 

CH3.COC1  +  C6H6  =  HC1  +  C6H5.CO.CH3. 

892.  For  these  preparations  equal  molecules  of  the  hydrocarbon 
and  the  acid  chloride  are  mixed   and  carbon  disulphide,  ligroine  or 
nitrobenzene  is  added  till  a  limpid  liquid  is  obtained.     Care  must  be 
taken  to  protect  from  all  moisture.    This  solution  is  added  a  little  at  a 
time  to  another  flask  which  contains  an  equal  volume  of  solvent  and 

81  SOMMELET,  Compt.  rend.,  157,  1443  (1913). 

22  FKIEDEL  and  CRAFTS,  Ann.  Chim.  Phys.  (6),  i,  478  (1884). 

23  ANSCHtiTZ,  Annakn,  235,  231  (1886). 

24  SILVA,  Compt.  rend.,  89,  606  (1879). 
26  DEMOLE,  Berichte,  12,  2245  (1879). 

26  GENVERESSE,  Bull.  Soc.  Chim.  (2),  49,  579  (1888). 

27  LINEBURGER,  Amer.  Chem.  Jour.,  13,  270  (1891). 

28  FRIEDEL  and  CRAFTS,  Bull  Soc.   Chim.   (2),  37,  6   (1882).  — E.   and  O. 
FISCHER,  Annalen,  194,  252  (1878).  —  ALLEN  and  KOLLIKER,  Annalen,  227,  107 
(1885). 


321  ELIMINATION  OF  HYDROGEN  893 

aluminum  chloride  equal  in  weight  to  the  acid  chloride.29  The  mix- 
ture is  warmed  slowly  on  the  water  bath  till  no  more  hydrogen  chlo- 
ride is  evolved. 

Nitrobenzene  as  a  solvent  has  the  advantage  of  dissolving  alu- 
minum chloride.30 

The  aluminum  chloride  may  be  added  a  little  at  a  time  to  the 
mixture  of  the  hydrocarbon  and  the  acid  chloride. 

893.  Results.  Acetyl  chloride,  CH3.COC1,  condenses  with  benzene 
to  form  acetophenone,  CeHs.CO.CHs,31  while  benzoyl  chloride,  CeHs.- 
COC1,  gives  benzophenone,  C6H5  .  CO  .  C6H5  32  which  may  also  be  ob- 
tained by  condensing  benzene  with  carbonyl  chloride.  Benzoyl  bromide 
may  be  used  with  benzene  and  aluminum  bromide.33 

Chlor-  brom-,  or  nitro-  ring  substitution  products  of  the  aromatic 
acid  chlorides  may  be  used  with  the  same  facility.  Thus  m.nitroben- 
zoyl  chloride,  02N.CeH4.COCl,  reacts  with  benzene  to  form  m.nitro- 
benzophenone,  O2N  .  CeH4  .  CO  .  CeH5,34  and  similar  compounds  can  be 
obtained  from  the  chlor  35  and  brom  36  derivatives. 

The  chlorides  of  dibasic  acids  can  give  a  double  reaction  to  form 
diketones.  Thus  succinyl  chloride  and  benzene  furnish  1,  J^-diphenyl- 
butadione(l,4),  Ce^.CO.C^.CE^.CO.CeHs.  The  reaction  is  car- 
ried out  in  carbon  disulphide.37 

Malonyl  and  glutaryl  chlorides  react  similarly.38 

On  account  of  its  tautomeric  nature,  phthalyl  chloride  can  give 
different  products  according  to  the  way  the  reaction  is  carried  out. 

Phthalophenone,  39  anthraquinone,          diphenyl-anthrone,  *° 

C(C6H5)2  C0  C(C6H6)2 


/  \  C6H  C6H4,  /   V 

CeH4v       ^>0,  \CO/  CeH4\n   / 

29  It  is  better  to  calculate  the  amount  from  its  molecular  weight  and  that  of 
the  acid  chloride;  to  1  mol.  RCOC1,  1  mol.  A1C18  -  133.5,  is  required  but  10% 
excess  is  of  advantage.  —  E.  E.  R. 

30  BEHN,  German  patent,  95,901  (1897). 

31  FEIEDEL  and  CRAFTS,  Ann.  Chim.  Phys.  (6),  14,  455  (1888). 

32  FRIEDEL  and  CRAFTS,  Ann.  Chim.  Phys.  (6),  i,  510,  and  518  (1884). 

33  OLIVIER,  Rec.  Trav.  Chim.  Pays-Bas,  37,  205  (1918). 

34  GEIGT  and  KONIGS,  Berichte,  18,  2401  (1885). 

35  OVERTON,  Berichte,  26,  29  (1893).  —  HANTZSCH,  Berichte,  24,  57  (1891).— 
DEMUTH  and  DITTRICH,  Berichte,  23,  3609  (1890). 

36  CATHCART  and  MEYER,  Berichte,  25,  1498  (1892). 

87  GLAUS,  Berichte,  20,  1375  (1887). 

88  AUGER,  Ann.  Chim.  Phys.  (6),  22,  349  (1891). 

39  FRIEDEL  and  CRAFTS,  Ann.  Chim.   Phys.   (6),   i,  523   (1884).  —  BAEYER, 
Annalen,  202,  51  (1880). 

40  HALLER  and  GUYOT,  Bull.  Soc.  Chim.  (3),  17,  873  (1897). 


894  CATALYSIS  IN  ORGANIC  CHEMISTRY  322 

o . benzoyl-benzoic  add,*1  C6H5 . CO . C6H4 . COOH,  and  other  products42 
are  obtained. 

Acid  chlorides  may  react  with  pyridine  or  quinoline  in  the  presence 
of  aluminum  chloride  to  give  ketones  when  traces  of  thionyl  chloride 
are  present.  From  benzoyl  chloride  and  pyridine,  pyridyl-phenyl-ketone 
is  obtained:43 

C6H6.CO.C1  +  C5H5N  =  HC1  +  C6H5 .  CO .  C5H4N. 

894.  Thiophosgene,  CSC12,  reacts  with  aromatic  hydrocarbons  to 
form   thioketones:    thus   with   benzene,   thiobenzophenone,    CeH6.CS.- 
C6H6.44 

m.  Formation  of  Amides 

895.  By  the  action  of  carbamic  chloride,  C1.CO.NH2,  aromatic 
amides  are  formed:   thus  from  benzene,  benzamide,  C6H5.CO.NH2  is 
obtained.46 

IV.  Formation  of  Cyclic  Compounds 

896.  Methylene  chloride  condenses  with  diphenyl,  C6H5.C6H5,  to 
form  fluorene, 

C6H4v 

;cH2.« 

C6H4/ 

897.  Tetrabromethane  (1,1,2,2,),  or  acetylene  tetrabromide,   reacts 
with  benzene  to  form  anthracene: 47 

BrCHBr  /CH\ 

C6H6  +       •          +  C6H6  =  C6H/  •       )C6H4  +  4HBr. 
BrCHBr  \CH/ 

Condensation  may  take  place  between  two  or  more  molecules  of  a 
chlor-compound.  Thus  2-phenyl-ethyl  chloride,  CeH5 .  CH2 .  CH2C1,  re- 
acts vigorously  with  aluminum  chloride  in  carbon  disulphide  or  lig- 
roine  to  form  an  insoluble  resin  (CeH4.CH2CH2)x. 

Dissolved  in  6  parts  of  ligroine  with  1  part  of  aluminum  chloride, 
4-phenyl-butyl  chloride  gives  an  excellent  yield  of  tetrahydro-naphtha- 
lene: 

/CH2 .  CH2 .  CH2  /CH2 .  CH2 

CeH4  •       =  C6H4  -       +  HC1. 

\H  C1CH2  \CH2.CH2 

41  SCHEIBER,  Annakn,  389,  121  (1912). 

42  COPISAROW,  J.  Chem.  Soc.,  in,  10  (1917). 

48  WOLFFENSTEIN  and  HARTWICH,  Berichte,  48,  2043  (1915). 
44  BERGREEN,  Berichte,  21,  341  (1888). 
46  GATTERMANN,  Annalen,  244,  29  (1888). 

46  ADAM,  Ann.  Chim.  Phys.  (6),  15,  253  (1888). 

47  ANTSCHtiTZ,  Annalen,  235,  165  (1886). 


323  ELIMINATION  OF  HYDROGEN  HALIDES  900 

Similarly  5-phenyl-pentyl  chloride  gives  phenyl-cyclopentane  boiling 
at  2130.48 

898.  Mechanism  of  the  Reaction.    We  have  shown  above  how  the 
role  of  the  aluminum  chloride  in  the  Friedel  and  Crafts  reaction  may 
be  explained  (173).    The  catalytic  nature  of  the  action  is  not  doubted 
though  sometimes  it  is  necessary  to  employ  large  amounts  of  the  salt, 
sometimes  larger  than  the  amount  of  the  aromatic  hydrocarbon.    This 
is  the  case  when  the  aluminum  chloride  combines  with  one  of  the 
products  of  the  reaction  and  is  thus  withdrawn  from  its  catalytic 
function.49 

899.  Other  Catalytic  Chlorides.    Several  anhydrous  metallic  chlo- 
rides can  be  employed  in  the  same  way  as  aluminum  chloride  in  the 
Friedel  and  Crafts  synthesis :  zinc,  ferrous,  ferric  and  stannic  chlorides 
and  antimony  pentachloride. 

The  use  of  ferric  chloride  is  quite  advantageous  in  preparing  ke- 
tones.50  Thus  benzoyl  chloride  and  benzene  give  benzophenone.™  Its 
action,  like  that  of  the  other  chlorides  mentioned  above,  is  milder 
than  that  of  aluminum  chloride.  For  that  reason  these  chlorides  some- 
times give  rise  to  less  formation  of  byproducts. 

For  the  preparation  of  benzophenone,  the  following  comparative 
yields  have  been  obtained: 51 

With  aluminum  chloride 70-71  % 

ferric  chloride 60-62 

zinc  chloride 28-32 

Aluminum  chloride  serves  poorly  for  condensing  toluene  with  chlor- 
methyl  ethers  (889),  while  good  results  are  obtained  with  antimony 
pentachloride  and  particularly  with  stannic  chloride.62 

The  use  of  zinc  chloride,  or  better  metallic  zinc  which  immediately 
forms  some  of  the  chloride,  has  been  recommended  for  reactions  with 
naphthalene.63  Thus  the  di-naphthyl  ketones  are  prepared  by  the 
action  of  zinc  on  a  mixture  of  naphthalene  with  a-  or  /3-naphthoyl 
chlorides.54 

900.  A  different  isomer  may  be  obtained  when  other  chlorides  are 
substituted  for  the  aluminum  chloride.     Isobutyl  chloride  condensed 

48  VON  BRAUN  and  DEUTSCH,  Berichte,  45,  1267  (1912). 

49  HELLER  and  ScntJLKE,  Berichte,  41,  3627  (1908). 

60  NENCKI,  Berichte,  30,  1766  (1897),  and  32,  2414  (1899).  —  MEISSEL,  Berichte, 
32,  2419  (1899). 

61  GANGLOFP  and  HENDERSON,  J.  Amer.  Chem.  Soc.,  39,  1420  (1917). 

62  SOMMELET,  Compt.  rend.,  157,  1443  (1913). 

63  ALEXYEF,  Meth.  de  transform,  des  comb,  organ.,  Paris,  1891,  186. 

64  GRUCAREVIC  and  MERZ,  Berichte,  6,  1242  (1877). 


901  CATALYSIS  IN  ORGANIC  CHEMISTRY  324 

with  toluene  in  the  presence  of  ferric  chloride  gives  p.methyl-isobutyl- 
benzene,  while  in  the  presence  of  aluminum  chloride  the  meta  com- 
pound is  obtained.65 

Formation  of  Aromatic  Amines  by  Hofmann's  Reaction 

901.  Traces  of  cuprous  iodide  can  readily  effect  the  condensation 
of  primary  aromatic  amines  with  phenyl  bromide,  with  elimination  of 
hydrobromic  acid.    The  acetyl  derivative  of  the  amine  may  be  used. 
Thus  by  boiling  90  g.  brombenzene,  10  g.  acetanilide,  6  g.  sodium 
carbonate  and  a  little  cuprous  iodide  for  15  hours,  acetyl-diphenyl- 
amine  is  obtained  and  this  can  readily  be  transformed  into  diphenyl- 
amine.    The  cuprous  iodide  can  be  replaced  by  copper  and  iodine  or 
even  by  copper  and  potassium  iodide.56 

The  presence  of  copper  powder  greatly  facilitates  the  action  of 
ammonia  under  pressure  at  170°  on  chlor-nitro-benzene  to  form  amino- 
nitro-benzene.57 

It  is  also  useful  in  the  similar  reaction  of  aniline  or  its  homologs  on 
o.chlor-benzoic  and  2,4-chlor-nitro-benzoic  acids  in  the  preparation  of 
the  corresponding  amino  compounds.67 

Likewise  pyridine  heated  7  hours  to  250°  with  benzyl  chloride  and  a 
little  copper  powder  gives  a  good  yield  of  2-benzyl-  and  4-benzyl- 
pyridine.  Ethyl  iodide  and  pyridine  give  the  ethyl-pyridines  under  the 
same  circumstances.  The  copper  can  be  replaced  by  cuprous  chloride. 
Aluminum  and  magnesium  powders  give  poorer  results.68 

Condensations  in  the  Aliphatic  Series  by  Anhydrous  Chlorides 

902.  The  use  of  ferric  chloride  enables  us  to  effect  important  con- 
densations in  the  aliphatic  series.    Thus  with  propionyl  chloride  in  the 
presence  of  alcohol,  two  molecules  of  the  acid  chloride  condense  to 
form  the  ester  of  a  keto-acid:™ 

CH3.CH2.COC1  +  CH3.CH2.COC1  +  C2H6OH  = 
CH3 .  CH2 .  CO .  CH  (CH,) .  C02C2H5  +  2HC1. 

903.  Chloroform  condenses  with  pentachlorethane  on  contact  with 
aluminum   chloride  with    evolution   of    hydrogen    chloride    to    form 
heptachlor-propane : 60 

CHC13  +  CC13.CHC12  =  HC1  +  CHC12 .  CC12 .  CC13. 

66  BIALOBRZESKI,  Berichte,  30,  1773  (1897). 

66  GOLDBERG,  Berichte,  40,  4541  (1907). 

67  ULLMANN,  Annalen,  355,  312  (1907). 

68  CHICHIBABINE  and  RYUMSHIN,  J.  Russian  Phys.  Chem.  Soc.,  47,  1297  (1915). 

69  HAMONET,  Bull.  Soc.  Chim.  (3),  2,  334  (1899). 
•°  PRINB,  J.  prakt.  Chem.  (2),  89,  414  (1914). 


325  ELIMINATION  OF  HYDROGEN  HALIDES  904 

§  3.  —  ELIMINATION   OF  A  MOLECULE   OF  AN 
ALKALINE   CHLORIDE,   BROMIDE,   OR  IODIDE 

904.  The  action  of  the  aromatic  halogen  derivatives,  phenyl  chlo- 
ride, bromide,  and  iodide  on  the  alkali  salts  of  phenol  should  form 
phenyl  ether,  but  practically  the  yield  is  trifling.  It  becomes  very  high 
when  the  reaction  is  carried  on  under  pressure  at  150°  to  200°  in  the 
presence  of  finely  divided  copper  as  catalyst.  The  yield  reaches  25  % 
with  the  chloride,  82%  with  the  iodide  and  78%  with  the  iodide. 

This  process  may  be  applied  to  the  formation  of  ethers  of  diphe- 
nols.61 

81  ULLMANN  and  SPONAGEL,  Annalen,  360,  83  (1907). 


CHAPTER  XXI 

DECOMPOSITIONS  AND  CONDENSATIONS 
OF  HYDROCARBONS 

905.  The  action  of  high  temperature  on  hydrocarbons  is  to  dis- 
sociate the  molecules,  from  which  hydrogen  tends  to  separate,  at  the 
same  time  that  it  produces  a  greater  or  less  breaking  up  of  the  mole- 
cules into  groups,  CH3,  CH2,  and  CH  which  are  capable  of  uniting  to 
form  new  complex  molecules.     There  result  complicated  mixtures  of 
varied  constitution  to  which  Berthelot  has  given  the  name  of  pyro- 
genetic  equilibria  which  as  the  temperature  rises  tend  to  produce  larger 
and  larger  proportions  of  hydrogen  and  methane  along  with  substances 
very  rich  in  carbon  and  very  condensed  hydrocarbons. 

906.  The  petroleum  industry  has  taken  advantage  of  reactions  of 
this  sort  in  the  process  known  as  "  cracking.11    This  process,  which  was 
accidentally  discovered  at  Newark,  N.  J.,  in  1861,  consists  in  carrying 
petroleum  vapors  to  high  temperatures,  above  a  dull  red.    Along  with 
usable  gases,  new  hydrocarbons  are  produced  which  increase  the  pro- 
portion either  of  gasoline  or  of  heavy  oils  as  compared  with  the  original 
oil. 

The  effect  of  temperature  begins  to  be  felt  at  about  325°  but  is  not 
important  below  a  red  heat.  The  presence  of  catalysts  lowers  the 
temperature  of  these  reactions  and  makes  them  easier  to  carry  out. 
The  finely  divided  metals,  copper,  iron,  cobalt,  nickel,  platinum,  mag- 
nesium, and  aluminum  can  be  employed  and  so  may  the  anhydrous 
oxides,  titania,  zinc  oxide  and  alumina,  etc.1 

It  is  important  to  know  the  results  of  the  pyrogenetic  decomposi- 
tion of  the  hydrocarbons  in  the  absence  of  catalysts. 

From  this  point  of  view,  benzene,  petroleums  and  the  coal  tar  hy- 
drocarbons known  as  solvent  naphtha  have  been  the  most  studied. 

907.  Benzene  is  hardly  affected  below  500°,  at  which  it  begins  to 
decompose  into   diphenyl,  the  formation  of  which  increases  till  it 
reaches  a  maximum  at  750°.    It  is  accompanied  by  diphenyl-benzene : 
carbon  is  deposited  and  hydrogen  set  free  without  any  production  of 
acetylene  or  of  naphthalene  below  8000.2 

1  ZELINSKI,  /.  Russian  Phys.  Chem.  Soc.,  47,  1808  (1915). 

2  ZANETTI  and  EGLOFF,  J.  Ind.  Eng.  Chem.,  9,  356  (1917). 

326 


327  DECOMPOSITIONS  OF  HYDROCARBONS  910 

908.  American  petroleum,  under  the  action  of  heat  alone,  gives  in- 
creasing amounts  of  gas  from  450°  to  875°,  while  the  density  of  the 
liquids  produced  increases  also  with  the  temperature.  Between  450° 
and  600°,  the  products  formed  contain  more  toluene  than  xylene,  more 
xylene  than  benzene,  and  neither  naphthalene  nor  anthracene.  At  650° 
the  proportion  of  benzene  is  still  lower  than  that  of  toluene  but  above 
that  of  xylene.  From  700°  to  850°,  benzene  is  more  abundant  than 
toluene  and  especially  than  xylene.  The  formation  of  naphthalene 
begins  at  750°  and  that  of  anthracene  at  800°  and  both  increase  rap- 
idly with  the  temperature. 

For  100  parts  of  petroleum  thus  treated,  the  benzene  in  the  prod- 


uct reaches  its  maximum  of  4.7%  at  750  ,  toluene  its  maximum  of 
3.1  %  at  650°,  and  xylene  its  maximum  of  1.9%  at  700°.  At  800°  we 
have  2%  naphthalene  and  0.3%  anthracene.  These  aromatic  hydro- 
carbons are  associated  with  various  aliphatic.3 

909.  Solvent  naphtha   contains   considerable   amounts   of   higher 
hydrocarbons.    When  it  is  heated  in  steel  tubes  under  11  atmospheres 
pressure  to  500-800°,  it  yields  considerable  amounts  of  lower  hydro- 
carbons.   In  the  product,  benzene  reaches  its  maximum  of  42.5  %  at 
800°  and  toluene  its  maximum  of  39.9  %  at  750°.    But  as  the  tempera- 
ture is  raised  higher  and  higher  the  yield  of  liquid  decreases  rapidly  in 
consequence  of  the  more  abundant  production  of  gaseous  products  and 
of  materials  poor  in  hydrogen,  the  real  maximum  yield  based  on  100 
parts  of  solvent  naphtha  is:4 

Benzene 15.9  %  at  800° 

Toluene 20.6  %  at  750°. 

Under  the  action  of  a  red  heat,  pinene  gives  a  large  number  of  hy- 
drocarbons, both  gaseous  and  liquid,  among  which  have  been  found 
benzene,  toluene,  m.xylene,  naphthalene,  anthracene,6  methyl-anthracene 
and  phenanthrene.6 

By  operating  at  a  barely  visible  red,  along  with  a  terpene  isomeric 
with  pinene  but  boiling  higher,  isoprene,  G&H.S,  benzene  and  its  homo- 
logs,  and  poly-terpenes  are  formed.7 

Action  of  Catalysts. 

910.  The  presence  of  catalysts  usually  enables  us  to  carry  out  the 
same  reactions  at  lower  temperatures  which  is  more  favorable  to  the 
preservation  of  sensitive  products  that  may  be  formed.     Usually 

EGLOFF  and  TWOMEY,  J.  Phys.  Chem.,  20,  121  (1916). 

EGLOFP  and  MOORE,  J.  Ind.  Eng.  Chem.,  9,  40  (1917). 

BERTHELOT,  Arm.  Chim.  Phys.   (3),  39,  5  (1853),  and  (4),  16,  165  (1869). 

SCHULTZ,  Berichte,  10,  114  (1877). 

TILDEN,  Ann.  Chim.  Phys.  (6),  5,  120  (1885). 


911  CATALYSIS  IN  ORGANIC  CHEMISTRY  328 

nickel  and  iron  act  violently  tending  to  produce  very  advanced  dehy- 
drogenation  with  charring  more  and  more  intense  as  the  temperature 
is  raised. 

911.  Aliphatic  Hydrocarbons.    Methane  is  only  slightly  attacked 
by  nickel  up  to  360°  but  towards  390°  the  deposition  of  carbon  is  ap- 
preciable.8 

The  decomposition  is  not  yet  rapid  at  910°  at  which  methane 
heated  10  minutes  in  a  porcelain  tube,  without  catalyst,  gives  only 
10%  of  hydrogen.  The  presence  of  silica  in  the  tube  does  not  in- 
crease the  decomposition,  but  with  lime  the  proportion  of  hydrogen 
reaches  35%,  with  wood  charcoal,  69%  while  with  metallic  iron  it  is 
78%.' 

Ethane  decomposes  slowly  above  325°  giving  carbon,  methane  and 
free  hydrogen. 

Pentane  decomposes  in  an  analogous  way  :  at  350-400°  methane  is 
produced  with  intermediate  hydrocarbons  and  carbon  is  deposited  on 
the  nickel. 

Lengthening  the  carbon  chain  makes  these  decompositions  more 
easy;10  but  only  above  550°  and  towards  600°  are  the  liquid  hydro- 
carbons such  as  are  found  in  Pennsylvania  petroleum  attacked. 

912.  Unsaturated  Hydrocarbons.    If  a  current  of  ethylene  is  passed 
over  reduced  nickel  heated  above  300°  the  nickel  can  be  seen  to  swell 
up  into  a  voluminous  black  material  which  finally  fills  the  tube  and 
chokes  it  up:   all  the  ethylene  disappears  and  a  gas  is  obtained  con- 
taining ethane,  methane,  and  hydrogen.     The  proportion  of  ethane  is 
less  with  higher  temperatures  of  the  metal :  at  a  dull  red  only  traces 
of  it  are  left. 

In  contact  with  nickel,  ethylene  is  decomposed  into  carbon  and 
hydrogen,  but  the  latter  is  taken  up  immediately  by  a  portion  of  the 
ethylene  to  form  ethane  which  is  more  and  more  broken  down  to 
methane  at  higher  temperatures.  The  nickel  is  found  diffused  in  the 
carbon  that  is  formed.11 

Propylene  suffers  an  analogous  destruction  but  more  slowly  and 
without  the  voluminous  swelling  of  the  metal.  The  decomposition  is 
appreciable  at  210°  and  is  clean  at  350°.  The  escaping  gas  contains 
propylene,  propane,  ethylene,  ethane,  methane  and  hydrogen.12 

All  other  unsaturated  hydrocarbons  give  analogous  results,  e.g.  the 

8  SABATIBR  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  435  (1905). 

9  SLATER,  J.  Chem.  Soc.,  109,  160  (1916). 

10  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  435  (1905). 

11  SABATIER  and  SENDERENS,  Compt.  rend.,  124,  616  and  1358  (1897). 

12  SABATIER  and  SENDERENS,  Compt.  rend.,  134,  1128  (1902). 


329  DECOMPOSITIONS  OF  HYDROCARBONS  915 

vapors  of  trimeihyl-eihylene  give  along  with  a  deposit  of  carbon,  the 
saturated  hydrocarbon  with  the  whole  series  of  lower  hydrocarbons. 

Cobalt  acts  in  a  similar  manner  but  less  actively  than  nickel.  With 
ethylene  at  360°  and  even  at  425°  there  is  slow  carbonization  without 
rapid  swelling  and  much  ethylene  survives. 

Iron  does  not  act  till  above  350°  and  gives  a  still  slower  decompo- 
sition. 

Platinum  (black  or  sponge)  and  reduced  copper  do  not  have  any 
appreciable  action  on  propylene  or  ethylene.13 

913.  Acetylene  Hydrocarbons.     Similar  dehydrogenating  actions, 
but  less  intense,  are  exercised  by  the  finely  divided  metals  on  the 
aletylene   hydrocarbons,  especially  acetylene.     The  action  can  be  di- 
vided into  two  entirely  distinct  kinds,  which  coexist.    One  of  these  is 
easily  observed  with  platinum  or  iron,  the  other  particularly  with  cop- 
per, while  nickel  superimposes  the  two  effects. 

914.  First  Kind  of  Reaction.     Pure  acetylene  when  heated  with 
platinum  to  150°,  is  rapidly  decomposed  into  carbon  and  hydrogen  : 
the  heat  evolved  by  this  decomposition  heats  the  metal  to  incandes- 
cence which  accelerates  the  destruction  giving  rise  to  a  great  carbon- 
aceous swelling,  and  which  causes  the  polymerization  of  the  remaining 
acetylene  into  benzene,   styrene,   and  hydrides  of  naphthalene  and 
anthracene  as  in  the  celebrated  synthesis  of  Berthelot.     This  phe- 
nomenon was  observed  by  Moissan  and  Moureu;14  it  is  complicated  by 
an  important  consecutive  action,  which  escaped  these  chemists  but 
which  Sabatier  and  Senderens  have  studied.16 

The  hydrogen  resulting  from  the  decomposition  of  one  portion  of 
the  gas  can  act  on  another  portion,  in  the  presence  of  platinum,  to 
form  ethylene  and  ethane.  The  liquid  collected  is  small  in  amount  and 
is  chiefly  benzene.  This  is  the  composition  by  volume  of  the  gases 
evolved : 

Acetylene 66.2% 

Benzene  (vapor) 2.8 

Ethylene 25.4 

Ethane 0.6 

Hydrogen •'  V  •   •.''*'.,.   .    .   .    .    .       5.0 

915.  A  much  greater  destructive  activity  belongs  to  reduced  iron 
(obtained  at  about  450°)  which  is  raised  by  acetylene  from  room  tem- 
perature to  incandescence.     If  the  tube  containing  the  iron  is  not 
heated,  the  reaction  almost  stops  with  the  local  decomposition  due  to 

13  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  436  (1905). 

14  MOISSAN  and  MOUREU,  Compt.  rend.,  122,  1241  (1896). 

16  SABATIER  and  SENDERENS,  Compt.  rend.,  131,  40,  187  and  267  (1900). 


916  CATALYSIS  IN  ORGANIC  CHEMISTRY  330 

the  incandescence,  the  formation  of  black  voluminous  carbon  in  which 
the  iron  is  disseminated  and  of  brown  liquids,  almost  entirely  aroma- 
tic. The  gases  remaining  are  little  but  surviving  acetylene  and  hy- 
drogen saturated  with  benzene  vapor.  But  if  the  entire  iron  tube  is 
kept  at  above  180°,  the  hydrogenation  of  the  acetylene  is  carried  on 
by  the  metal  beyond  the  incandescent  portion  so  that  little  acetylene 
is  left  and  the  gas  is  only  hydrogen,  ethylene  and  ethane  with  the 
vapors  of  higher  hydrocarbons. 

916.   Second  kind  of  Reaction.    This  is  caused  by  copper. 

If  a  current  of  acetylene  is  passed  over  light  copper  (obtained  by 
reduction  at  a  low  temperature)  at  180°  the  copper  is  seen  to  turn 
brown  at  once  and  the  pressure  diminishes  greatly  on  account  of  the 
rapid  condensation  of  the  acetylene  in  contact  with  the  metal.  Some- 
times the  current  of  acetylene  which  was  20  cc.  per  minute  is  entirely 
taken  up  for  more  than  20  minutes  and  then  slowly  begins  to  pass. 
At  this  moment  the  copper  is  seen  to  swell  rapidly  taking  on  a  lighter 
tint  of  brown  and  soon  filling  the  tube  so  as  to  stop  the  flow  of  gas. 

The  condensed  liquid  is  a  mixture  of  unsaturated  and  aromatic 
hydrocarbons  (benzene,  styrene  etc.),  the  presence  of  the  styrene  caus- 
ing partial  solidification  after  a  time.16  The  small  amount  of  gas  that 
passes  out  contains,  with  a  small  amount  of  acetylene,  hydrogen, 
ethane  and  particularly  the  unsaturated  hydrocarbons,  ethylene, 
propylene  and  butylene,  which  constitute  more  than  two  thirds  of  it. 

The  copper  is  found  disseminated  in  the  entire  brown  solid  mate- 
rial formed.  If  a  small  portion  of  this  is  placed  as  a  layer  in  another 
tube  and  heated  to  180-250°  in  a  current  of  acetylene,  the  material 
swells  up,  again  filling  the  tube.  One  can  start  anew  with  a  portion 
of  this  material  and  fill  another  tube.  After  three  or  four  such  swell- 
ings, a  material  is  obtained  which  is  no  longer  changed  when  heated 
in  acetylene.  This  is  a  lighter  or  darker  brown  solid  which  appears 
under  the  microscope  to  be  a  thick  felt  of  very  fine  filaments.  It  is 
light  and  fluffy  and  may  be  agglomerated  into  masses  resembling 
tinder.  It  is  a  hydrocarbon  of  the  empyrical  formula  CyHe  in  which 
is  found  diffused  a  little  copper  (about  1.5%)  which  has  caused  its 
formation  :  this  is  cuprene.17  Its  composition  is  identical  with  that  of 
the  condensed  hydrocarbon  formed  by  the  decomposition  of  benzyl 
chloride  by  metallic  chlorides  (880)  or  by  the  dehydration  of  benzyl 
alcohol  (714),  and  is  perhaps  hexaphenyl-cyclohexane,  CeHXCeHs^.18 

16  On  account  of  polymerization  of  the  styrene  to  a  solid.  —  E.  E.  R. 

17  SABATIEB  and  SENDERENS,  Bull.  Soc.  Chim.  (3),  21,  530  (1899).  —  Compt. 
rend.,  130,  250  (1900).  —  SABATIER,  3rd  Congress  on  Acetylene,  Paris,  1900,  345 
and  4th  Cong.  Applied  Chem.,  Paris,  1900,  3,  134. 

18  SABATIER  and  MAILHE,  Ann.  Chim.  Phys.  (8),  20,  298  (1918). 


331  DECOMPOSITIONS  OF  HYDROCARBONS  918 

The  formation  of  cuprene  is  doubtless  due  to  the  formation  of  an  un- 
stable acetylide  capable  of  reacting  with  acetylene  to  form  a  new  con- 
densed molecule,  thus  : 

nC2H2  +  nCu  =  nC2Cu  +  nH2 
and  nC2Cu  +  6nC2H2  =  (C6H7)2n  +  nCu. 

cuprene         regenerated 

The  regenerated  metal  is  capable  of  repeating  the  reaction  indefi- 
nitely. The  hydrogen  set  free  combines  with  a  portion  of  the  acety- 
lene over  the  copper  to  give  chiefly  ethylene  hydrocarbons. 

Compact  copper,  in  sheet  or  wire,  gives  a  similar  formation  when 
heated  in  acetylene  to  200-50°  and  covers  itself  with  a  brown  coat- 
ing which  becomes  more  yellow  as  its  thickness  increases. 

917.  Superposition  of  the  Two  Kinds  of  Reaction.    If  over  a  layer 
of  reduced  copper  heated  at  its  middle  portion  to  above  250°  a  rapid 
current  of  acetylene  be  passed,  incandescence  accompanied  by  intense 
swelling  is  observed  at  this  point  and  there  is  simultaneous  production 
of  carbon  and  of  cuprene  formed  by  the  superposition  of  the  two 
reactions. 

918.  Reduced  nickel  usually  causes  both  reactions.     If  the  re- 
duced nickel  is  entirely  freed  from  the  hydrogen  absorbed  by  its 
particles,  it  no  longer  becomes  spontaneously  incandescent  in  acetylene 
and  can  be  heated  to  150°  before  it  causes  a  reaction.    It  is  only  above 
180°,  that  a  slow  reaction  takes  place,  without  incandescence,  and  this 
reaction  remains  thus  if  the  passage  of  the  gas  is  not  too  rapid.    The 
metal  turns  black  and  swells  a  little,   covering  itself  with  a  solid 
brownish  fibrous  silky  hydrocarbon  which  suggest  cuprene;   but  this 
formation  is  slow  and  if  one  tries  to  accelerate  it  by  passing  the  acely- 
lene  more  rapidly  or  by  elevating  the  temperature,  incandescence 
appears  bringing  rapid  decomposition  with  charring. 

Usually  when  acetylene  is  passed  over  a  layer  of  recently  reduced, 
nickel  without  precautions,  there  is  immediate  spontaneous  incandes- 
cence, brought  on  by  the  occluded  hydrogen,  and  carbonizing  decom- 
position takes  place  always  followed  by  the  hydrogenation  of  the 
acetylene  and  of  a  part  of  the  aromatic  hydrocarbons  resulting  from 
the  incandescence  because  the  nickel  is  capable  of  effecting  such  hy- 
drogenations. 

Summing  up,  nickel  acting  on  acetylene  at  180°  produces  a  triple 
effect : 

1st.  Rapid  decomposition  into  carbon  and  hydrogen  with  poly- 
merization to  aromatic  hydrocarbons. 

2nd.  Slow  condensation  into  a  solid  hydrocarbon  doubtless  identi- 
cal with  cuprene. 


919  CATALYSIS  IN  ORGANIC  CHEMISTRY  332 

3rd.  Hydrogenation  of  the  acetylene  and  of  the  aromatic  hydro- 
carbons with  production  of  aliphatic,  unsaturated  and  cyclo-aliphatic 
hydrocarbons. 

With  a  tube  that  is  not  externally  heated,  where  the  incandescence 
is  intense  and  localized  at  a  single  point,  the  first  effect  is  the  greatest, 
the  velocity  of  the  gas  rendering  the  subsequent  hydrogenation 
unimportant.  These  are  the  conditions  studied  by  Moissan  and 
Moureu. 

919.  With  cobalt  quite  free  from  nickel  and  reduced  from  oxide  at 
below  350°,  incandescence  is  not  obtained,   starting  with  the  tube 
cold,  but  is  readily  started  by  heating  some  point  on  the  tube,  and  is 
easily  maintained  if  the  tube  is  heated  to  200°.    The  action  is  inter- 
mediate between  that  of  iron  and  that  of  nickel.     The  tube  is  filled 
with  a  black  mass  consisting  of  carbon  in  which  the  cobalt  is  diffused 
and  traces  of  a  hydrocarbon  analogous  to  cuprene   can  be  seen.19 

920.  The  effects  of  nickel,  iron,  cobalt  and  copper  are  much  less 
intense  when  these  metals  are  employed  in  the  form  of  sheets  and  have 
appeared  to  many  observers  negligible  even  up  to  600°.     On  the  con- 
trary magnesium  powder  acting  at  600°  on  methane,  ethane,  ethylene 
and  acetylene  causes  a  95%  decomposition.     Aluminum  powder,  at 
near  the  fusion  point  of  the  metal,  causes  a  total  decomposition  while, 
platinum  decomposes  only  80  %.20 

Hexane,  under  high  pressure,  is  attacked  energetically  at  650-700° 
in  an  iron  tube  in  the  presence  of  alumina.21 

921.  Cyclic  Hydrocarbons.     As  has  been  said  above    (640),  the 
hydro-cyclic  hydrocarbons  in  contact  with  finely  divided  metals  form 
the  corresponding  aromatic  hydrocarbons  by  loss  of  hydrogen;    but 
the  cyclic  hydrocarbons,  benzene,  its  homologs,  naphthalene,  anthra- 
cene etc.  are  themselves  attacked,  and  tend  to  be  resolved  into  CH2 
and  CH  groups  like  those  furnished  by  the  aliphatic  hydrocarbons. 
Metallic  oxides  also  can  catalyze  decompositions  of  this  sort. 

Finely  divided  nickel,  iron  and  cobalt  act  energetically  above  400° 
and  especially  at  a  dull  red  heat,  on  the  hydro-cyclic  hydrocarbons, 
among  which  are  the  terpenes,  and  cause,  along  with  dehydrogenations 
which  take  place  at  lower  temperatures  (640),  decompositions  more 
and  more  serious  as  the  temperature  is  raised,  and  accompanied  by 
carbonaceous  deposits  which  increase  at  the  same  time.  The  charring 
is  less  intense  with  copper. 

The  aromatic  hydrocarbons,  benzene  and  its  homologs,  are  much 

19  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  430  (1905). 

w  KUSNETZOW,  Berichte,  40,  2871  (1907). 

21  IPATIEP  and  DOVGELEVICH,  J.  Russian  Phys.  Chem.  Soc.,  43,  1431  (1911); 
C.  A.,  6,  736  (1912). 


333  DECOMPOSITIONS  OF  HYDROCARBONS  924 

less  affected  by  the  action  of  finely  divided  metals  than  when  they  are 
acted  on  in  the  nascent  state,  that  is  when  they  are  being  formed  by 
the  dehydrogenation  of  cyclohexane  or  terpene  hydrocarbons. 

922.  The  Case  of  Pinene.    The  action  of  heat  on  pinene  when  its 
vapors  are  passed  through  a  red  hot  tube  has  been  described  above 
(909).    The  tube  being  of  iron  and  sometimes  filled  with  broken  pum- 
ice or  porcelain  the  peculiar  influence  of  the  metal  or  of  the  filling 
may  enter  into  the  reaction. 

By  passing  these  vapors  over  very  light  finely  divided  copper  (59), 
in  a  glass  tube  heated  to  600-30°,  a  rapid  evolution  of  gas  of  high 
illuminating  power  consisting  of  hydrogen  charged  with  the  vapors  of 
lower  hydrocarbons,  is  obtained.  By  conducting  the  operation  very 
slowly,  100  cc.  of  pinene  gave  81  cc.  of  condensate  which  contained  : 

13.3  cc.  passing  over  below  95° 
27.0  cc.  passing  over  from      95°  to  150° 

31.4  cc.  passing  over  from    150°  to  185° 
9.3  cc.  passing  over  above  185°. 

Treatment  with  sulphuric  acid,  which  dissolves  the  terpenes  and 
the  ethylenic  and  di-ethylenic  hydrocarbons,  reduced  the  volume  to 
31.5  cc.  of  hydrocarbons  almost  entirely  nitrifiable  and  consisting  of 
about  19  cc.  cymene  and  methyl-ethyl-benzene,  10  cc.  m.  xylene  and 
toluene  and  a  small  amount  of  benzene.  In  the  most  volatile  portion 
of  the  hydrocarbons  is  found  some  isoprene,  hardly  more  than  2  cc. 
The  terpenes  remaining  in  the  product  have  no  effect  on  polarized 
light. 

923.  Reduced  nickel  acts  more  violently  than  copper  at  600°  and 
causes  intense  carbonization  in  consequence  of  its  destructive  action 
on  ethylenic  and  di-ethylenic  hydrocarbons  (912).    The  gas  is  richer 
in  hydrogen,  the  liquids  condensed  are  less  and  contain  a  considerable 
proportion  of  saturated  hydrocarbons  resulting  from  the  hydrogenat- 
ing  action  of  the  metal  on  the  unsaturated  hydrocarbons  and  un- 
attacked  by  either  sulphuric  or  nitric  acid.22 

Reactions  carried  out  in  the  Presence  of  Hydrogen 

924.  The  decompositions  of  the  hydrocarbons  by  the  metals  cor- 
respond to  an  elimination  of  hydrogen  of  which  a  portion  is  utilized 
for  hydrogenating  the  fragments.    It  seemed  probable  that  the  pres- 
ence of  hydrogen  with  the  hydrocarbon  molecules  would  stabilize 
them  or  would  favor  the  hydrogenation  of  the  fragments  resulting 
from  their  decomposition.    The  stabilization  is  actually  realized  in  the 

22  SABATIEK,  MAILHE  and  GAUDION,  Compt.  rend.,  168,  826  (1919). 


925  CATALYSIS  IN  ORGANIC  CHEMISTRY  334 

case  of  the  cyclohexane  hydrocarbons  which  are  preserved  to  a  great 
extent  (640),  in  the  case  of  the  aromatic  hydrocarbons  derived  from 
the  terpenes  (644).  Hydrogenation  carried  out  at  temperatures  at 
which  the  hydrocarbons  are  broken  up  would  necessarily  lead  to  the 
hydrogenation  of  the  fragments  that  would  be  formed  in  the  absence 
of  the  hydrogen. 

925.  Acetylene.    We  have  seen  (423)  that  the  direct  hydrogena- 
tion of  acetylene,  carried  out  over  cold  nickel  or  at  a  low  temperature, 
gives  ethane  accompanied  by  a  certain  amount  of  higher  aliphatic 
hydrocarbons,  both  gaseous  and  liquid:  the  reason  for  the  formation 
of  these  by-products  being  the  breaking  up  of  the  molecule  HC  •  CH, 
which  takes  place  at  near  room  temperature,  thereby  liberating  the 
CH  groups  which  are  hydrogenated  to  methane,  CH4,  or  to  the  groups 
CH2  and  CH3,  the  groups  CH3,  CH2  and  CH  being  able  to  unite  in 
various  ways  to  give,  in  the  cold,  more  or  less  complex  aliphatic  hy- 
drocarbons.    By  operating   continuously  for  24   hours  with   nickel 
maintained  at  200°,  Sabatier  and  Senderens  condensed  about  20  cc.  of 
a  clear  yellow  liquid  with  a  splendid  fluorescence  and  an  odor  quite 
similar  to  that  of  rectified  petroleum.     It  began  to  boil  at  about  45°  and 
half  of  it  passed  over  below  150°,  while  at  250°  there  remained  a  small 
quantity  of  very  fluorescent  orange  yellow  liquid,  certainly  containing 
poly  cyclic  hydrocarbons.     The  original  liquid  had  a  density  of  0.791 
at  0°  and  was  slightly  attacked  by  the  nitro-sulphuric  acid  mixture 
which  extracted  a  small  amount  of  aromatic  hydrocarbons.     The  re- 
maining oil  had  a  density  of  0.753  at  0°  and  was  composed  almost 
entirely  of  aliphatic  hydrocarbons  (pentane,  hexane,  heptane,  octane, 
nonane,  decane,  undecane  etc.)  which  were  associated  in  the  original 
product  with   unsaturated   hydrocarbons,  soluble  in  slightly  diluted 
sulphuric  acid,  and  with  traces  of  aromatic  hydrocarbons.    The  com- 
position, odor,  density  and  fluorescence   class  this  liquid  with  Penn- 
sylvania petroleums. 

926.  If  through  a  tube  containing  reduced  nickel  and  kept  be- 
tween 200  and  300°,  a  rapid  current  of  pure  acetylene  is  passed,  with- 
out hydrogen,  a  lively  incandescence  is  obtained  on  account  of  the 
decomposition  of  the  acetylene  into  carbon  and  hydrogen   (918).      A 
portion  of  the  acetylene  thus  carried  to  a  high  temperature  condenses 
to  benzene  and  other  aromatic  hydrocarbons  according  to  the  reaction 
discovered  by  Berthelot;    another  portion  breaks  up  into  CH  groups 
which  can  be  hydrogenated  along  with  the  aromatic  hydrocarbons  by 
the  portion  of  the  nickel  layer  which  remains  at  200-300°.     In  the 
receiver  is  collected  a  considerable  amount  of  liquid,  greenish  by  re- 
flected light,  reddish  by  transmitted,  the  appearance  of  which  greatly 


335  DECOMPOSITIONS  OF  HYDROCARBONS  930 

resembles  crude  petroleum.  If  this  liquid  is  hydrogenated  directly 
over  nickel  at  200°  a  colorless  liquid  is  obtained  which  is  only  slightly 
attacked  by  the  nitro-sulphuric  acid  reagent  and  which,  on  fractiona- 
tion,  gives  a  whole  series  of  liquids  of  densities  similar  to  those  of  the 
corresponding  fraction  of  Caucasian  petroleum.  The  chief  constituents, 
as  in  the  petroleum  fractions,  are  the  polymethylene  hydrocarbons 
resulting  from  the  hydrogenation  of  the  aromatic  hydrocarbons  formed 
by  the  incandescence.  As  in  the  Caucasian  petroleum  there  are  cer- 
tain amounts  of  aliphatic  hydrocarbons  resulting  from  the  hydrogena- 
tion of  the  CH  groups  which  are  set  free  and  then  reunited  in  various 
fashions. 

927.  By  causing  incandescence  in  mixtures  of  acetylene  and  hy- 
drogen, the  proportion  of  the  aliphatic  hydrocarbons  is  increased  and 
the    poly-methylenes    diminished    and    intermediate    petroleums    are 
obtained. 

If  the  hydrogenation  following  the  incandescence  takes  place  at 
about  300°,  the  cyclohexane  hydrocarbons  are  formed  only  incom- 
pletely and  are  accompanied  by  certain  proportions  of  untransformed 
aromatic  hydrocarbons  :  we  have  Galician  petroleum. 

928.  Analogous  reaction  can  be  effected  by  finely  divided  cobalt 
and  to  a  certain  extent  by  iron.    Sabatier  and  Senderens,  who  found 
out  the  above  facts,  have  based  on  them  a  simple  theory  of  the  gene- 
sis of  natural  petroleum.    There  are  doubtless  far  down  in  the  earth's 
crust  large  masses  of  alkaline  and  alkaline  earth  metals  as  well  as  of 
the  carbides  of  these  metals.    Water  penetrating  through  fissures  in  the 
rocks  and  coming  in  contact  with  these  materials  will  evolve  hydro- 
gen and  acetylene,  in  proportions  which  will  doubtless  vary  greatly. 

If  the  hydrogen  is  in  large  excess,  the  gaseous  mixture,  coming  in 
contact  with  nickel,  cobalt  or  iron  disseminated  in  adjacent  rocks  at 
temperatures  which  may  be  lower  than  200°,  gives  rise  to  American 
petroleum  and  at  the  same  time  to  large  quantities  of  combustible 
gases  in  whch  are  found,  as  in  the  natural  gas  of  the  Pittsburgh  dis- 
trict, much  methane,  ethane  and  free  hydrogen.23 

Use  of  Anhydrous  Aluminum  Chloride 

929.  Anhydrous  aluminum  chloride  heated  with  aliphatic  hydro- 
carbons, tends  to  decompose  them  into  lower  and  higher  hydrocarbons. 
Amylene  gives  methane  at  the  same  time  as  hexane  and  still  more  con- 
densed hydrocarbons.24 

930.  More  important  and  more  regular  effects  are  observed  with 

23  SABATIER  and  SENDERENS,  Ann.  Chim.  Phys.  (8),  4,  445  (1905).  —  SABATIER, 
Rev.  Mois,  i,  257  (1906). 

14  ASCHAN,  Annalen,  324,  1  (1902). 


931  CATALYSIS  IN  ORGANIC  CHMEISTRY  336 

aromatic  hydrocarbons,  as  has  been  stated  above  (887),  tending  to  their 
degradation  and  building  up  at  the  same  time.  Ethyl-benzene  heated 
with  aluminum  chloride  is  degraded  to  benzene,  while  diethyl-benzene 
is  formed  to  compensate  (888). 

A  xykne  (in  which  the  meta  predominated)  boiled  for  5  minutes 
with  2  %  anhydrous  aluminum  chloride  in  an  apparatus  with  a  me- 
chanical stirrer  gave  29%  of  hydrocarbons  boiling  below  135°.  Pro- 
longed boiling  raised  the  yield  only  to  34  %,  nor  does  increasing  the 
amount  of  the  chloride  increase  it  sensibly.  Benzene  is  formed  chiefly 
with  a  little  toluene.  The  proportion  of  toluene  is  no  better  when  the 
operation  is  carried  on  under  18  atmospheres  pressure.25 

Cymene  heated  with  a  third  of  its  weight  of  aluminum  chloride 
gives  a  mixture  which  contains  :  2  %  benzene,  42  %  toluene,  and  7  % 
xylene  (chiefly  meta)  with  a  little  di-isopropyl-benzene  and  methyl-di- 
isopropyl-benzene,  increasing  the  amount  of  the  catalyst  increases  the 
amount  of  the  benzene  and  decreases  the  toluene.26 

931.  Naphthalene  heated  in  an  autoclave  at  330°  under  10  atmos- 
pheres pressure,  for  20  minutes  with  4  %  anhydrous  aluminum  chloride 
gives,  along  with  a  carbonaceous  and  tarry  material,  32  %  of  a  liquid 
hydrocarbon  of  which  about  half  is  dihydro-naphthalene  resulting  from 
the  hydrogenation  of  one  part  of  the  naphthalene  at  the  expense  of 
another.27 

Under  the  action  of  anhydrous  aluminum  chloride,  pinene  gives 
pentane  and  its  homologs  as  well  as  cyclohexene  hydrocarbons.28 

Application  to  the  Treatment  of  Petroleums 

932.  The  use  of  catalysts  enables  us  to  improve  greatly  the  opera- 
tion of  cracking  (906)  for  the  purpose  of  increasing  the  volatile  portion 
of  petroleum,  since  it  lowers  greatly  the  temperature  at  which  the 
reaction  takes  place  thus  permitting  the  survival  of  molecules  result- 
ing from  the  decomposition  which  would  otherwise  be  attacked  at  the 
higher  temperatures. 

If  over  finely  divided  metals,  such  as  powdered  iron  or  reduced 
copper,  maintained  at  a  temperature  between  400°  and  a  dull  red,  the 
vapors  of  a  crude  petroleum  (from  any  source)  or  of  petroleum  pre- 
viously stripped  of  its  gasoline,  there  is  partial  decomposition  into  a 
mixture  of  hydrogen  and  gaseous  hydrocarbons  and  liquids  of  which  a 
considerable  proportion  distils  below  150°  and  may  be  separated. 

26  F.  FISCHER  and  NIGGEMANN,  Berichte,  49,  1475  (1916). 

26  SCHORGER,  /.  Amer.  Chem.  Soc.,  39,  2671  (1917). 

27  F.  FISCHER,  Berichte,  49,  252  (1916). 

28  STEINKOPP  and  FREUND,  Berichte,  47,  411  (1914). 


337  DECOMPOSITIONS  OF  HYDROCARBONS  933 

When  the  residue  is  again  submitted  to  the  action  of  finely  divided 
metals,  a  new  amount  of  volatile  liquids  is  formed,  and  so  on. 

The  gases  evolved  are  quite  abundant  and  are  composed  of  satu- 
rated and  unsaturated  hydrocarbons  having  high  calorific  and  illum- 
inating power. 

Iron  has  the  inconvenience  that  it  causes  an  abundant  deposit  of 
carbon  on  its  surface.  Copper  causes  much  less  of  this  but  requires  a 
higher  temperature,  near  to  600°;  temperatures  below  550°  give  poor 
results  while  above  800°  there  is  intense  carbonization  with  diminu- 
tion of  the  yield  of  gasoline. 

Thus  starting  with  an  American  petroleum  containing  nothing 
boiling  below  150°,  by  a  single  passage  over  copper  at  600°,  1  1.  gave 
225  cc.  gasoline  boiling  below  150°.  At  the  same  time  120  1.  of  gas 
was  evolved  with  high  illuminating  power  and  having  a  heating  power 
of  15,000  calories  per  cu.  m. 

After  some  time  the  copper  becomes  too  much  fouled  with  carbon- 
aceous materials  and  does  not  have  sufficient  activity.  In  order  to 
regenerate  it  all  that  is  necessary  is  to  pass  over  it  a  current  of  steam 
which  causes  the  carbon  to  disappear  without  altering  the  metal  while 
producing  water  gas  which  may  be  used  for  heating  the  apparatus. 

The  liquids  thus  obtained  are  composed  in  part  of  saturated  and 
aromatic  hydrocarbons  and  in  part  of  hydrocarbons  containing  one  or 
two  double  bonds.  These  are  oxidisable  and  polymerizable  and  have  a 
disagreeable  odor.  In  the  experiment  cited  above  their  proportion 
was  40%. 

In  order  to  transform  them  into  saturated  compounds  without 
disagreeable  odors  it  is  sufficient  to  hydrogenate  their  vapors  in  the 
presence  of  finely  divided  metals  (particularly  reduced  nickel)  between 
150°  and  300°.  A  hydrocarbon  is  thus  obtained  that  may  be  used  as 
gasoline.  Furthermore,  the  two  phases  of  the  process  can  be  com- 
bined so  as  to  transform  continously  a  crude  petroleum  or  petroleum 
residue  into  gasoline,  of  which  as  high  as  75%  may  be  obtained.29 

933.  Numerous  patents  have  been  taken  out  for  processes  of  this 
sort.  One  proposes  to  use  finely  divided  metals  at  600°  under  6  at- 
mospheres pressure.30 

In  another  patent,  the  gas  issuing  from  the  catalytic  cracking  is 
charged  with  ammonia  and  thus  modified  is  used  to  carry  along  the 
vapors  of  the  hydrocarbon  over  metal  oxides  which  can  be  reduced  to 
the  metal.  The  nascent  hydrogen  set  free  by  the  decomposition  of  the 
ammonia  by  the  metal,  saturates  the  hydrocarbons  and  diminishes  the 

29  SABATIER,  French  patent,  400,141,  May,  1909. 

»°  HALL,  English  patent,  17,121,  of  1913;   /.  S.  C.  /.,  33,  1149  (1914). 


934  CATALYSIS  IN  ORGANIC  CHEMISTRY  338 

amount  of  the  carbonaceous  deposits.  By  this  process  gasoline  free 
from  sulphur  is  obtained  even  from  Mexican  petroleum  containing  5  % 
of  sulphur.31 

934.  Catalytic  oxides   (titania,  alumina,  and  zinc  oxide)  can  also 
be  utilized  for  such  transformations,  particularly  for  changing  Russian 
cyclohexane  petroleums  into  aromatic  hydrocarbons   (benzene,  toluene 
and  homologs).    A  benzine  from  Baku  (98  to  102°)  gave  30%  of  aro- 
matic hydrocarbons  of  which  over  half  was  toluene. 

The  use  of  iron  retorts  is  to  be  avoided  on  account  of  the  intense 
carbonization  which  this  metal  causes  and  the  rapid  deterioration 
which  results  therefrom.32 

935.  Aluminum  chloride  enables  us  to  carry  out  analogous  re- 
actions at  much  lower  temperatures  (929). 

Petroleum  freed  from  water  and  gasoline  is  heated  24  to  48  hours 
with  dry  aluminum  chloride.  The  products  obtained  are  almost  en- 
tirely saturated  and  it  is  unnecessary  to  treat  them  with  sulphuric 
acid,  washing  with  soda  and  then  with  water  being  sufficient  to  get 
rid  of  the  hydrogen  sulphide.  The  aluminum  chloride  is  regenerated 
by  submitting  the  residual  coke  to  a  current  of  chlorine  at  a  red  heat. 
The  yield  of  gasoline  from  Oklahoma  petroleum,  which  gives  only 
12.5%  by  the  ordinary  cracking  process,  is  raised  to  34.8%  by  this 
method.33 

936.  Iron  chlorides,  although  less  active,  may  be  substituted  for 
the  aluminum  chloride,  and  with  Russian  oils,  very  poor  in  gasoline, 
a  certain  amount  of  hydrocarbons  passing  over  from  40°  to  140°  is 
obtained.    Of  this  about  35  %  is  hexane  and  heptane  while  the  rest  is 
chiefly  7  and  8  carbon  cyclic  hydrocarbons.    Heavy  hydrocarbons  the 
consistence  of  which  resembles  asphalt,  are  produced  at  the  same 
time.34 

81  VALPY  and  LUCAS,  English  patent  20,470  of  1913  and  2,838  of  1914;  J.  Soc. 
Chem.  Ind.,  34,  71  (1915). 

82  ZELINSKI,  J.  Russian  Phys.  Chem.  Soc.,  47,  1807  (1915). 
33  McAFEB,  /.  Ind.  Eng.  Chem.,  7,  737  (1915). 

84  PICTET  and  LERCZYNSKA,  Bull.  Soc.  Chim.  (4),  19  (1916). 


SUPPLEMENT  TO   CHAPTERS   XI  AND   XII 
HYDROGENATION   OF  LIQUID   FATS 

937.  The  liquid  fats,  oils  of  various  origins,  contain  along  with  the 
neutral  glycerine  esters  of  the  saturated  acids,  (CnH2nO2,)  palmitic, 
margaric,  stearic,  arachidic  etc.,  a  considerable  proportion  of  the 
glycerine  esters  of  the  unsaturated  acids,  either  ethylenic  acids, 
(CnH2n_202,)  hypogalc,  olew,  elaldic,  erucic  etc.,  or  diethylenic, 
(CH2n_4O2,)  as  linoleic,  or  unsaturated  hydroxy  as  ridnoleic,  or  still 
more  unsaturated  acids  as  linolenic,  CigHaoO-j  and  clupadonic,  CisH^Ojj. 
The  unsaturated  acids  and  their  glycerine  esters  have  much  lower 
melting  points  than  the  corresponding  saturated  compounds,  thus  : 


Stearic  acid,  CisHseOu  .....  melts  at          71° 

Oleic  acid,  CisH^C^  .....  melts  at          14° 

Ricinole'ic  acid,  Ci8H34O3  .....  melts  at          26° 

Linoleic  acid,  Ci8H32O2  .....  melts  below  -18°. 

Stearine,  or  glycerine  tristearate,  melts  at  71.5°  while  olelne,  or 
glycerine  trioleate,  is  liquid  at  the  ordinary  temperature.  In  some 
cases  these  unsaturated  compounds  have  disagreeable  odors.  The 
presence  of  clupadonic  acid  is  responsible  for  the  repulsive  odor  of  fish 
oils. 

938.  The  absorption  of  iodine  by  fats  gives  an  exact  measure  of 
the  amounts  of  unsaturated  acids  that  enter  into  their  constitution. 

By  the  term  iodine  number  we  mean  the  amount  of  iodine  ab- 
sorbed by  100  parts  of  the  fat.1 

The  following  table  gives  the  average  value  of  the  iodine  number 
for  a  number  of  different  fats: 

Cocoa  butter     .....    ..,..*..  36 

Mutton  or  beef  tallow    ....    %.   ...  35  to    47 

Hog  lard     ...    .....   ,.."....  44  to    70 

Goose  fat    ...........   .   .   v  .  77 

Olive  oil      ......  .../'.*    .   .  V  ..^  .  82 

Colza  oil.    .    .    .    ...   „  ,  ,.  v  ...   .  ';.>-  ;.  100 

1  HtteL,  Dingler's  Polytech.  /.,  253,  281  (1884). 

339 


939  CATALYSIS  IN  ORGANIC  CHEMISTRY  340 

Almond  oil 98 

Castor  oil 84 

Peanut  oil 97 

Cottonseed  oil . 109 

Sesame  oil 108 

Poppy  seed  oil 133  to  158 

Whale  oil 127 

Cod  liver  oil 140  to  180 

Linseed  oil      180 

Clupadonic  acid 365  to  370. 

939.  By  adding  hydrogen  and  thereby  transforming  unsaturated 
glycerides  into  saturated,  the  bad  odors  of  certain  oils  (fish  and  co- 
coanut)  disappear  and  the  melting  points  are  greatly  raised. 

When  applied  to  the  oils  themselves,  hydrogenation  changes  them 
into  solid  fats,  i.e.  more  and  more  solid  the  more  the  ole'ine  is  trans- 
formed into  stearine. 

Sabatier  and  Senderens  showed  between  1897  and  1902  that  hy- 
drogen is  easily  added  to  ethylene  bonds  in  the  presence  of  reduced 
nickel  at  temperatures  below  250°  and  it  was  desired  to  apply  this 
method  to  the  hydrogenation  of  the  liquid  fatty  acids  or  to  the  oils 
themselves.  It  is  possible  by  dragging  the  vapors  of  oleic  acid  by  a 
violent  current  of  hydrogen  over  nickel  at  280°  to  transform  it  com- 
pletely into  stearic  add.  A  column  of  reduced  copper  can  effect  the 
same  reaction  at  300°  and  in  this  case  the  hydrogen  may  be  replaced 
by  water  gas.2 

In  the  patents  of  Bedford,3  the  fatty  material  vaporized  in  hydro- 
gen under  reduced  pressure  is  hydrogenated  while  traversing  a  vertical 
cylinder  filled  with  nickeled  pumice  heated  to  200°,  but  the  lowering 
of  the  pressure  of  the  gas  is  unfavorable  to  its  fixation. 

940.  The  difficulty  of  volatilizing  the  liquid  fatty  acids  and  the 
practical  impossibility  of  volatilizing  the  oils  themselves  led  to  the 
abandonment  of  the  reaction  on  the  vapors  and  to  attempts  to  effect 
it  in  the  liquid  material.     The  patent  of  Norman  of  1903  compre- 
hended hydrogenation  of  the  vapor  and  of  the  liquid.4 

It  is  to  hydrogenation  in  the  liquid  medium  that  almost  all  of  the 
very  numerous  patents  applying  to  this  important  industrial  problem 
relate  :  more  than  200  have  been  taken  out  on  the  choice,  preparation 
and  method  of  using  catalysts  or  for  apparatus. 

2  SABATIER,  French  patent,  394,957  (1907). 

1  BEDFORD  and  WILLIAMS,  English  patent,  9,112  of    1908.  —  BEDFORD,   U.  S. 
patent,  949,954  (1910). 

4  NORMAN,  English  patent,  1,515  of  1903. 


341  HYDROGEN  OF  LIQUID  FATS  943 

941.  Catalysts.     Nickel  is  most  frequently  employed  being  used 
alone  in  the  finely  divided  state  as  is  obtained  by  the  reduction  of  the 
oxide  with  hydrogen,  or  more  commonly  incorporated  with  an  inert 
material  intended  to  disseminate  it  and  to  increase  the  useful  surface 
of  contact  with  the  hydrogen  and  oil.     For  this  purpose  have  been 
used   nickeled   pumice,6  kieselguhr,    or  infusorial   earth,  impregnated 
with  nickel6,  nickeled  asbestos7,  and  wood  charcoal  impregnated  with 
nickel.8    The  method  of  incorporating  the  nickel  with  the  carrier  may 
vary  :  for  example,  the  nickel  is  dissolved  in  sulphuric  acid  and  double 
its  weight  of  siliceous  material  is  added  (pumice,  kaolin,  asbestos  etc.) ; 
the  metal  is  precipitated  as  the  carbonate  which  is  calcined  to  form 
the  oxide  which  is  thus  distributed  over  every  fragment  of  the  porous 
material,  and  the  oxide  is  reduced  by  hydrogen  at  350°. 9 

942.  It    has    been    suggested    to  use   the   finely   divided   nickel 
formed  in  the  decomposition  of  nickel  carbonyl  by  heat.     Finely  di- 
vided nickel  is  kept  suspended  in  oil  at  above  180°  and  a  current  of 
carbon  monoxide  or  of  water  gas  is  passed  through.    This  transforms 
the  metal  into  nickel  carbonyl  which  immediately  breaks  down  into 
carbon  dioxide,  carbon  and  finely  divided  nickel  which  remains  sus- 
pended in  the  liquid  and  is  ready  to  realize  its  hydrogenation  at   a 
somewhat  higher  temperature,  around  220-40°. 10    Practically  the  nickel 
thus  formed  may  be  only  0.1  %  of  the  oil  to  be  hydrogenated. 

It  has  been  proposed  to  impregnate  pumice  or  kieselguhr  with 
nickel  carbonyl  and  then  heat  it  to  liberate  the  metal  which  should  be 
perfectly  spread  over  the  porous  material :  the  catalyst  thus  prepared 
is  incorporated  in  the  oil  to  be  treated  without  coming  in  contact  with 
the  air.11 

943.  The  substitution  of  nickel  oxides  for  metallic  nickel  has  put 
over  against  existing  patents,  other  patents  which  could  not  be  of 
value  if  the  oxide  does  not  act  until  after  it  has  been  reduced  to  the 
metal,   as   various   investigations   seem  to   have   established    (598). 

6  NORMAN,  English  patent,  1,515  of  1903.  —  BEDFORD  and  WILLIAMS,  English 
patent,  9,142  of  1908.  —  ERDMANN,  German  patents,  211,669,  C.,  1910  (1),1906,  and 
222,890  (1907),  C.  A.,  4,  2715  (1910). 

6  KAYSER,  U.  S.  patents,  1,004,035  and  1,008,474  (1911),  /.  8.  C.  I.,  30,  1266 
and  1461  (1911).  — WILBUSCHEWITCH,  French  patent,  426,343  (1910),  /.  S.  C.  I., 
30, 966  (1911).—  CROSSFIELD  and  MARKEL,  French  patent,  435,249  (1911),  J.  S.  C.7., 
3,  346  (1912). 

7  SCHWOERER,  German  patent,  199,909  (1906)). 

s  ELLIS,  U.  S.  patent,  1,060,673,  (1913),  C.  A.,  7,  2132  (1913).  — ITTNER,  Mat. 
grasses.  1918,  4964.' 

9  WILBUSCHEWITCH,  English  patent,  15,439  of  1911,  J.  S.  C.  I.,  30,  1170  (1911) 

10  SHUKOFF,  German  patent,  241,823  (1910),  C.,  1912  (1),  175. 

11  SCHICHT,  Mat.  grasses,  1916,  4634. 


944  CATALYSIS  IN  ORGANIC  CHEMISTRY  342 

This  substitution,  inspired  by  the  work  of  Ipatief  (584),  has  been 
advised  by  Bedford  and  Erdman,  who  believe  that  the  most  active 
catalyst  is  a  sub-oxide  such  as  N2O,12  and  has  been  frequently  applied 
to  the  hydrogenation  of  oils.13 14 

944.  Various  salts  of  nickel  have  been  proposed  to  replace  the 
oxide  as  catalyst.    Nickel  borate  recommended  by  Schonfeld  15  as  being 
very  active,  has  been  found  by  other  chemists  absolutely  useless  unless 
broken  down  to  the  oxide  by  a  temperature  of  above  260°,  the  presence 
of  the  boric  acid  appearing  to  be  unfavorable.16 

The  nickel  salts  of  organic  acids,  acetate,  lactate,  and  especially  the 
formate  have  shown  themselves  useful.17  The  product  produced  by 
heating  nickel  formate  in  a  current  of  nitrogen  has  been  advised.18 

945.  The  other  common  metals  near  to  nickel,  iron,  cobalt  and 
copper  have  been  rarely  used  although  they  figure  along  with  nickel  in 
a  large  number  of  patents.19    The  same  is  true  of  platinum  on  account 
of  its  high  price  which  is  not  compensated  for  by  any  special  activity. 

946.  Palladium  on  the  contrary,  has  been  recommended  as  a  cata- 
lyst for  oils  in  spite  of  its  high  cost  because  of  its  remarkable  activity, 
1  part  of  metal  effecting  the  hydrogenation  of  10,000 20  parts  of  oil  be- 
low 100°.     It  is  advantageously  employed  at  about  80°  under  2  or  4 
atmospheres  of  hydrogen.21    It  is  best  to  use  the  palladium  precipi- 
tated on  an  inert  carrier,  either  animal  charcoal  or  a  metallic  oxide  or 

12  BEDFORD  and  ERDMANN,  /.  prakt.  Chem.  (2),  87,  425  (1913). 

13  BEDFORD  and  WILLIAMS,  French  patents,  418,355   (1910);    436,295   (1911); 
J.  S.  C.  I.,  31,  444  (1912).  —English  patent,  29,612  of  1910,  J.  S.  C.  I.,  31,  398 
(1912).  —  U.  S.  patent,  1,026,339  (1912),  J.  S.  C.  /.,  31,  593  (1912).—  BEDFORD  and 
ERDMANN,  French  patent,  451,155  (1912),— J.  S.  C.  L,  32,  602  (1913). 

14  The  exact   comparative  experiments  of  WILLSTATTER  and  WALDSCHMIDT- 
LEITZ  (Berichte,  54,  131,  (1921))  go  far  towards  proving  that  nickel  is  entirely  in- 
active unless  it  contains  some  oxygen.    Using  0.2  g.  nickel  in  20  cc.  water  with 
1  g.  sodium  cinnamate,  no  hydrogen  was  taken  up  in   1  hour  at  60°  but   the 
catalyst  was  activated  by  shaking  with  oxygen  for  15  minutes.     A  number    of 
similar    experiments    are   cited.    A   quantitative   experiment   showed   that   the 
amount  of  oxygen  absorbed  by  a  sample  of  nickel,  exposed  to  the  air,  was  not 
weighable  yet  the  nickel  was  activated  by  this  exposure.  —  E.  E.  R. 

15  SCHONFELD,  Zeit.  }.  angew.  Chem.,  27  (2),  601  (1914),  C.  A.,  8,  3868  (1914). 

16  ERDMANN  and  RACK,  Zeit.  f.  angew.  Chem.,  28,  220  (1915),  C.  A.,  9,  1255 
(1915). 

17  WIMMER  and  HIGGINS,  French  patent,  441,097  (1912),  J.  S.  C.  /.,  31,  826 
(1912). 

18  HIGGINS,  Mat.  grasses,  1917,  4760. 

19  NORMAN,  English  patent,  1,515  of  1903,  J.  S.  C.  I.,  23,  26  (1904).  — WIL- 
BUSCHEWITCH,  French  patent,  426,343  (1910),  /.  S.  C.  I.,  30,  966  (1911). 

20  Hydrogenation  of  cottonseed  oil  may  be  carried  on  at  180°  with  this  propor- 
tion of  nickel  on  a  carrier.  —  E.  E.  R. 

21  DAY,  U.  S.  patent,  826,089  (1906),  /.  S.  C.  I.,  25,  1035  (1906). 


343  HYDROGEN  OF  LIQUID  FATS  949 

carbonate  or  magnesium  or  nickel,  the  use  for  this  purpose  of  iron, 
lead,  zinc  or  aluminum  being  unfavorable.22 

The  chief  disadvantage  in  the  use  of  palladium  is  its  excessive  cost 
since  some  loss  of  metal  is  inevitable,  the  cost  according  to  experience 
amounting  to  1.60  francs  per  100  kg.  oil  treated. 

947.  Life  of  Catalysts.     Certain  substances  when  found  in  even 
small  amounts  in  the  oils,  paralyze  the  activity  of  catalysts  and  do 
not  take  long  to  render  them  inactive  (112).    The  most  to  be  feared 
in  the  hydrogenation  of  oils  are  sulphur  compounds. 

Hydrogen  sulphide  immediately  renders  inactive  100  times  its 
weight  of  nickel  and  pulverized  sulphur  is  half  as  effective.  The  action 
is  less  rapid  with  the  same  proportion  of  sodium  sulphide.  On  the 
contrary,  sulphates,  sodium  nitrate,  and  nickel  chloride  have  no  harm- 
ful effect.  Free  chlorine  kills  the  nickel  instantly.23  24 

In  contact  with  fish  oil  and  whale  oil  the  catalyst  is  quickly 
killed;  the  toxic  material  is  fixed  by  the  metal  since  if  a  fresh  cata- 
lyst is  added  hydrogenation  takes  place.  Consequently  a  practical 
method  of  purification  of  these  oils  is  to  agitate  them  with  a  spent 
catalyst  which  abstracts  the  harmful  substances. 

948.  Oils  frequently  contain  free  fatty  acids  which  attack  the 
nickel  to  the  detriment  of  its  catalytic  activity.    Hence  it  is  best  to 
neutralize  them  by  agitation  with  pulverized  calcium  carbonate  or  with 
a  small  amount  of  dilute  cold  sodium  carbonate  solution.    The  neutral 
oil  thus  obtained  may  be  effectively  freed  from  its  toxic  materials  by 
agitating  it  hot  with  freshly  precipitated  cupric  hydroxide.25 

949.  The  presence  of  moisture  in  the  oil  or  in  the  hydrogen  can 
lead  to  a  certain  amount  of  saponification  at  the  elevated  tempera- 
ture at  which  the  reaction  is  carried  out,  hence  it  is  important  to 
avoid  the  presence  of  water  and  to  dry  the  gas  before  using  it,  e.g.,  by 
refrigeration  to  -200.26 

22  VEREINIGTE  CHEM.  WERKE,  German  patent,  236,488  (1910),  C.  A.,  5,  3633 
(1911).  —  French  patents,  427,729  and  434,927  (1911),  /.  S.  C.  I.,  30,  1022  and 
31,346  (1912).  —  English  patent,  18,642  of  1911,  C.  A.,  7,  555  (1913). 

23  MOORE,  RICHTER,  and  ARSDEL,  J.  Ind.  Eng.  Chem.,  9,  451  (1917). 

24  It  is  suggested  by  WILLSTATTER  and  WALDSCHMIDT-LEITZ  (Berichte,  54,  127. 
(1921),  that  the  poisoning  of  catalysts,  by  certain  substances,  at  least,  may  be  due 
to  the  fact  that  they  deprive  the  catalysts  of  their  oxygen  content  and  thereby 
render  them  inactive.    They  show  that  thiophene  removes  the  oxygen  from  plat- 
inum black.    In  an  experiment  in  which  1.9  g.  benzene  was  being  hydrogenated 
in  acetic  acid  solution  by  means  of  0.5  g.  platinum  black,  1.5  mg.  thiophene  was 
added  whereby  the  activity  of  the  catalyst  was  completely  destroyed.    The  cata- 
lyst recovered  87  %  of  its  original  activity  by  treatment  with  oxygen  for  2  hours. 
—  E.  E.  R. 

26  ELLIS  and  WELLS,  Mat.  grasses,  1917,  4760. 

26  Soc.  DE  STEARIN.  ET  SAVON.  DE  LYON,  French  patent,  485,414  (1917). 


950  CATALYSIS  IN  ORGANIC  CHEMISTRY  344 

950.  Nickel  catalysts  that  have  been  rendered  inactive  by  long 
use  are  regenerated  by  degreasing  and  treating  with  nitric  acid  and 
calcining  the  nitrated  material  thus  obtained. 

951.  Amount  of  Catalyst.    The  weight  of  catalyst  can  vary  much 
according  to  the  work  it  has  to  accomplish.    The  rapidity  of  the  re- 
action is  nearly  proportional  to  the  amount  of  catalyst  used.     It  is 
usually  best  not  to  cut  down  the  amount  of  the  catalyst  since  it  is 
convenient  to  shorten  the  time  of  the  hydrogenation  as  much  as  pos- 
sible.    Usually  2  or  3  %  of  nickel  distributed  on  an  inert  material  is 
employed.     With  palladium  the  amount  of  catalyst  may  be  much 
smaller.27 

952.  Temperatures.    The  temperatures  most  frequently  employed 
for  hydrogenations  with  nickel  are  around  180°  but  may  sometimes  be 
as  low  as  150°  and  are  frequently  raised  to  200-50°  especially  when 
the  oxide  is  used. 

Much  lower  temperatures  suffice  with  palladium,  usually  80  to 
100°. 

Elevation  of  temperature  increases  the  speed  of  the  reaction 
greatly.  In  the  neighborhood  of  170-80°  with  nickel,  raising  the  tem- 
perature 10°  increases  the  velocity  about  20  %.28 

953.  Hydrogen.       The    hydrogen    for    hydrogenations   may    be 
prepared  electrolytically  or  may  be  produced  as  a  by-product  in  the 
manufacture  of  caustic  soda. 

It  can  also  be  obtained  by  the  action  of  steam  on  incandescent 
coke,  the  water  gas  thus  formed,  after  absorption  of  the  carbon  di- 
oxide, being  partially  liquefied  to  eliminate  the  carbon  monoxide.  But 
it  is  more  frequently  prepared  by  the  decomposition  of  water  by  me- 
tallic iron,  the  iron  oxide  so  formed  being  reduced  at  a  red  heat  by 
water  gas. 

This  decomposition  can  take  place  at  a  red  heat  alternating  with 
the  reduction  of  the  iron  oxide  which  is  thus  formed;  but  under  these 
conditions  it  is  difficult  to  avoid  the  presence  of  a  certain  amount  of 
carbon  monoxide  which  it  is  important  not  to  admit  in  appreciable 
amount. 

Amounts  of  0.25  to  2%  of  carbon  monoxide  produce  a  serious 
diminution  in  the  activity  of  the  catalyst;  6  or  8%  prevent  any  hy- 
drogenation by  the  nickel  either  by  forming  a  deposit  of  carbon  which 
covers  the  catalyst  (614),  or  because  the  carbon  monoxide  turns  the 
catalytic  activity  of  the  nickel  to  its  own  use  in  transforming  itself 

27  Good  results  on  cottonseed  oil  may  be  obtained  with  0.1  %  of  nickel  dis- 
tributed on  10  parts  of  carrier.  —  E.  E.  R. 

28  MOORE,  RICHTER  and  VAN  ARSDEL,  J.  Ind.  Eng.  Chem.,  9,  451  (1917).  — 
Mat.  grasses,  1918,  5018. 


345  HYDROGEN  OF  LIQUID  FATS  956 

to  methane.29  This  toxicity  of  carbon  monoxide  is  all  the  more  pe- 
culiar since  nickel  carbonyl  has  no  harmful  effect  when  it  is  sent  into 
the  oil  with  the  hydrogen,  even  in  large  amount,  and  since  the  nickel 
resulting  from  its  decomposition  is,  up  to  a  certain  limit,  superior  to 
reduced  nickel.30 

The  result  is  that  water  gas  containing  about  equal  volumes  of  hy- 
drogen and  carbon  monoxide  with  a  little  carbon  dioxide  and  nitrogen, 
which  can  give  good  results  with  copper  as  a  catalyst  (515),  is  pro- 
scribed in  the  hydrogenation  of  oils  over  nickel. 

954.  According  to  Bergius,  the  formation  of  hydrogen  by  water 
and  iron  can  be  very  advantageously  carried  out  by  operating  with 
water  kept  in  the  liquid  form  by  high  pressures.    By  working  under 
300  atmospheres  at  300-40°,  the  reaction  : 

3Fe  +  4H2O  =  4H2  +  Fe3O4. 

takes  place  completely  and  can  be  greatly  accelerated  by  the  presence 
of  sodium  chloride  or  ferrous  chloride  along  with  metallic  copper. 
Under  exactly  the  same  experimental  conditions,  the  amounts  of  hy- 
drogen evolved  per  hour  were : 

Iron  and  water  alone  at  300° 230  cc. 

Iron,  water  and  FeCl2  at  300° 1390 

Iron,  water,  FeCl2  and  Cu  at  300° 1930 

Iron,  water,  FeCl2  and  Cu  at  340° 3450 

An  apparatus  holding  45  1.  can  produce  102  cu.  m.  per  day.  The 
iron  oxide  obtained  is  in  fine  powder  and  easy  to  reduce  to  metallic 
iron  by  water  gas. 

The  hydrogen  thus  prepared  is  very  pure  since  the  iron  carbides 
and  sulphides  which  are  in  the  iron  are  not  attacked  by  liquid  water. 
The  hydrogen  evolved  under  a  pressure  of  300  atmospheres  can  be 
stored  in  steel  cylinders  without  further  compression.31 

955.  The  volume  of  hydrogen  required  for  hydrogenation  varies 
with  the  proportion  and  nature  of  the  unsaturated  acids  which  enter 
into  the  composition  of  the  oils. 

For  pure  olelc  acid  about  79  cu.  m.  per  100  k.  of  acid  are  required 
while  linolew  acid  requires  twice  and  clupadonic  add  four  times  this 
amount. 

29  MAXTED,  Trans.  Faraday  Soc.,  13,  36  (1918). 

30  MAXTED,  Trans.  Faraday  Soc.,  13,  201  (1918). 

31  BERGIUS,  J.  Soc.  Chem.  Ind.,  32,  463  (1913).  —  German  patents,  254,593  and 
286,961. 


956  CATALYSIS  IN  ORGANIC  CHEMISTRY  346 

The  corresponding  glycerides  require  somewhat  less,  about  76  cu. 
m.  for  oleine.  The  amount  required  by  an  oil  is  proportional  to  its 
iodine  number;  linseed  oil  requires  150  cu.  m.  per  1000  k.  32 

956.  Pressure.     It  is  advantageous  to  operate  under  pressures 
higher  than  atmospheric,  the  velocity  of  the  hydrogenation  being,  at 
least  up  to  a  certain  limit,  proportional  to  the  pressure  of  the  hydro- 
gen.    In  practice,  pressures  of  2  to  15  atmospheres  are  used. 

957.  Apparatus.    A  large  number  of  forms  of  apparatus,  many  of 
which  differ  only  in  details,  have  been  devised  for  the  hydrogenation 
of  oils.    Contrary  to  the   general  impression,  it   is  not  necessary  to 
agitate  the  oil  and  the  catalyst  very  violently  with  the  hydrogen;  the 
agitation  should  especially  have  the  effect  of  replacing  hydrogenated 
portions  of  the  oil  in  contact  with  the  catalyst  by  portions  not  yet 
acted  on. 

The  various  forms  of  apparatus  may  be  divided  into  four  distinct 
types  : 

958.  First  Type.     The  oil  and  hydrogen  are  simultaneously  pro- 
jected on  to  a  catalytic  surface. 

This  is  the  principle  of  the  apparatus  of  Erdmann  which  is  com- 
posed of  a  vertical  nickel  cylinder  in  the  centre  of  which  a  vertical 
concentric  terra  cotta  cylinder  covered  with  a  layer  of  catalyst  with  a 
nickel  base,  turns  slowly;  the  apparatus  is  heated  to  180°  and  the  oil 
driven  by  compressed  hydrogen  is  projected  onto  the  surface  of  the 
cylinder  and  runs  down  after  it  is  acted  upon.33 

959.  In  the  apparatus  of  Schwoerer  designed  to  hydrogenate  oleic 
acid,  the  acid  carried  along  by  steam  superheated  to  250-70°  and 
mixed  with  hydrogen  is  projected  on  to  a  helicoidal  surface  covered 
with  nickeled  asbestos.34 

960.  The  apparatus  of  Schlinck  belongs  in  this  class;    it  is  com- 
posed of  a  centrifuge  which  turns  on  a  vertical  axis  in  a  closed  cylinder 
at  the  top  of  which  oil  and  compressed  hydrogen  are  introduced  to- 
gether.    The  basket  of  the  centrifuge  is  furnished  with  asbestos  im- 
pregnated with  catalyst  (specially  palladium).    The  oil  on  account  of 
the  rapid  rotation,  the  hydrogen  on  account  of  its  pressure  traverse 

32  The  volume  of  hydrogen  required  to  saturate  any  oil  is  readily  calculated 
from  its  iodine  number.  Thus  1  K  of  oil  whose  iodine  number  is  1,  requires 
882.0  cc.,  or  1000  K  requires  0.8820  cu.m.,  of  hydrogen  measured  at  0°  C.  and 
760  mm.  Hence  multiply  these  figures  by  the  iodine  number  of  the  oil  in  ques- 
tion. 1  K  cottonseed  oil  with  iodine  number  110  would  take  97.02  1.  to  saturate 
it  completely  or  35.28  1.  of  hydrogen  to  bring  it  down  to  an  iodine  number  of  70. 
—  E.  E.  R. 

88  ERDMANN,  German  patent,  211,669  (1907),   C.  A.,  3,  2732. 

M  SCHWOERER,  German  patent,  199,909  (1906). 


347  HYDROGEN  OF  LIQUID  FATS  962 

this  layer  simultaneously  and  partially  combine.  The  partially  hydro- 
genated  oil  runs  out  at  the  bottom;  the  partially  expanded  hydrogen 
passes  out  at  the  side  of  the  top  of  the  cylinder  and  is  recompressed  to 
be  sent  into  another  cylinder  along  with  the  partially  treated  oil. 
After  passing  through  a  sufficient  number  of  cylinders  exactly  alike 
the  oil  is  completely  hydrogenated.35 

961.  Second  Type.    The  oil  mixed  with  the  catalyst  is  atomized 
in  an  atmosphere  of  hydrogen  which  is  kept  at  a  suitable  tempera- 
ture by  steam  heat. 

The  apparatus  of  Wilbuschewitch  which  seems  to  have  given  good 
results  belongs  here.  It  is  composed  of  an  autoclave  in  the  form  of  an 
elongated  vertical  cylinder  the  lower  end  of  which  terminates  in  a  60° 
cone  which  is  kept  at  160°.  The  oil  to  which  the  pulverulent  catalyst 
has  previously  been  added  and  which  is  kept  mixed  by  a  suitable 
rotating  apparatus,  is  atomized  at  the  top  of  the  cylinder  where  the 
falling  droplets  encounter  an  ascending  current  of  hydrogen.  This 
enters  at  the  lower  tip  of  the  cone  through  a  circular  chamber  the  top 
of  which  is  perforated  with  holes,  passes  through  the  oil  which  has 
accumlated  in  the  cone,  then  up  the  cylinder  where  it  encounters  the 
droplets  of  oil  with  the  catalyst  and  passes  out  at  the  top  of  the  cylin- 
der to  be  used  again.  The  partially  hydrogenated  oil  which  accumu- 
lates in  the  cone  is  sent  with  the  catalyst  which  it  carries  into  a  second 
autoclave  like  the  first  where  the  hydrogenation  is  carried  further  and 
so  on  into  other  cylinders  till  the  desired  hydrogenation  is  obtained.36 

962.  Third  Type.    The  hydrogen  is  atomized  into  oil  holding  the 
catalyst  in  suspension  and  heated  to  a  known  temperature. 

This  is  the  principle  of  one  form  of  apparatus  of  Ellis,  which  con- 
sists of  a  conical  heating  vessel  with  vertical  axis  having  its  apex  at 
the  bottom  and  heated  by  circulation  of  high  pressure  steam  in  a 
double  jacket.  It  is  filled  with  oil  for  two  thirds  of  its  height.  The 
catalyst  is  added  through  a  hole  in  the  top  and  the  hydrogen  admitted 
at  the  desired  pressure  is  circulated  by  means  of  a  pump,  being  drawn 
from  the  top  and  forced  in  at  the  bottom  of  the  cone  rising  through 
the  oil  which  it  agitates  and  which  it  hydrogenates  thanks  to  the  cata- 
lyst which  is  suspended  in  it.  The  passage  of  the  gas  is  continued 
till  the  desired  degree  of  hydrogenation  is  attained.  At  this  moment  a 
horizontal  circular  filtering  disc  which  is  operated  by  a  rod  which  oc- 
cupies the  axis  of  the  cone,  is  lowered  till  it  rests  on  the  walls  of  the 
cone  near  the  apex.  The  oil  is  filtered  through  this  disc  leaving  the 

86  SCHLINCK,  German  patent,  252,320  (1911),  C.  A.,  7,  910  (1913).  —  English 
patent,  8,147  of  1911,  C.  A.,  6,  2858  (1912). 

36  WILBUSCHEWITCH,  French  patent,  426,343  (1910),  /.  S.  C.  I.,  30,  966  (1911). 
—  English  patent,  30,014  of  1910,  J.  S.  C.  I.,  31,  443  (1912). 


\    n 

963  CATALYSIS  IN  ORGANIC  CHEMISTRY  348 

catalyst.     The  apparatus  can  be  charged  with  a  fresh  portion  of  oil 
which  takes  up  the  same  catalyst.87 

963.  Fourth  Type.     A  vigorous  agitation  brings  the  oil,  catalyst 
and  hydrogen  together  in  the  same  vessel. 

Kayser's  apparatus  consists  of  an  autoclave  heated  to  150-60°  and 
filled  one  fourth  full  of  oil  mixed  with  a  pulverulent  nickel  catalyst 
under  hydrogen  introduced  at  the  desired  pressure.  An  agitator  con- 
sisting of  six  vanes  of  metal  cloth  mounted  on  a  metal  frame  perpen- 
dicular to  a  horizontal  axis,  can  revolve  rapidly  and  thus  cause  an 
intimate  mixture  of  gas,  oil  and  solid  catalyst.38 

964.  The  apparatus  of  Kimura  is  very  similar.39    In  the  apparatus 
of  Woltmann  the  agitator  rotates  on  a  horizontal  axis  and  carries 
perforated  arms  through  which  the  hydrogen  is  sent  in  under  pressure 
corresponding  to  the  rate  of  its  fixation  by  the  oil.40 

965.  Results.     The  hydrogenation  of  oil  is  carried  on  in  quite  a 
large  number  of  plants,  more  than  24  in  1916. 

It  enables  us  to  obtain  from  oils  of  very  inferior  quality,  such  as 
whale  oil,  fatty  materials  with  odors  that  are  not  disagreeable,  pos- 
sessing a  remarkable  consistence  along  with  high  melting  points.  A 
regulated  hydrogenation  enables  us  to  prepare  at  will  products  inter- 
mediate between  the  oils  and  the  solid  fats. 

The  fixation  of  1  %  by  weight  of  hydrogen  is  sufficient  to  transform 
cottonseed  oil  and  other  oils  of  that  class  into  substances  with  the 
consistency  of  lard.  This  result  may  be  attained  directly  by  means  of 
hydrogenation  of  the  whole  mass  of  the  oil  and  stopped  at  the  desired 
hardness,  the  operation  being  carried  on  at  as  low  a  temperature  as 
possible  so  as  not  to  alter  the  qualities  of  the  oil.  But  the  desired  end 
can  be  more  surely  attained  by  hydrogenating  a  portion  of  the  oil  to 
the  limit  and  then  mixing  this  with  untreated  oil  to  obtain  the  de- 
sired hardness. 

966.  The  table  below  gives  the  melting  points  of  the  fats  obtained 
by  complete  hydrogenation  of  the  oils  or  fats.41 

*7  ELLIS,  J.  Soc.  Chem.  Ind.,  31,  1155  (1912). 

"  KATSER,  U.  S.  patents,  1,004,035  and  1,008,474  (1911),  /.  S.  C.  I.,  30,  1266 
and  1461  (1911). 

39  KIMURA,  French  patent,  486,621  (1918). 

40  WOLTMAN,  English  patent,  112,293  (1916),  C.  A.,  12,  1006  (1918). 

41  MANNICH  and  THIELE,  Mat.  grasses,  1917,  4676. 


349  HYDROGEN  OF  LIQUID  FATS  96$ 

Melting  points 

Hydrogenated  oil    Original 

Olive  oil 70°  6° 

Almond  oil 72°  -10° 

Peanut  oil .               64.5°  -  3 

Sesame  oil 63.5°  -5° 

Poppy  seed  oil 70.5°  -18° 

Linseed  oil 68°  -16° 

Codliver  oil 68°  -10° 

Cocoa  butter 64°  23° 

Tallow 62°  35° 

Lard  oil 64°  28° 

The  iodine  number  becomes  very  small  in  every  case. 

967.  The  commercial  grades  do  not  correspond  to  such  complete 
hydrogenation.    They  exhale  a  peculiar,  very  persistent  aromatic  odor 
which  resists  saponification  and  distillation  under  reduced  pressure. 

Such  hardened  oils  are  known  under  the  French  trade  names  of 
duratol,  talgol,  candelite  and  synthetic  tallow. 

Below  are  given  some  of  the  characteristics  of  such  products, 
melting  point,  iodine  number  and  melting  point  of  the  fatty  acids  :  ®  ** 

M.p.  I.  No.  M.p.  of  Acids. 

Talgol 35-37°  86.1  38.5° 

Talgol  extra 42-44°  63.9  45.5° 

Candelite 48-50°  10.4  48.5° 

Candelite  extra 51-52°  10.5  51.8° 

968.  Castor  oil  which  does  not  solidify  till  below  -18°,  gives  on 
careful  hydrogenation  a  very  white  hard  solid  which  melts  above  80° 
and  which  is  advantageously  employed  as  an  electric  insulator. 

969.  The  question  of  the  use  of  deodorized  and  hardened  oils  as 
fats  in  food  has  not  been  completely  settled  as  yet,  because  we  are  not 
altogether  certain  about  the  toxicity  of  the  small  amounts  of  nickel 
which  remain  in  the  materials,  amounts  that  are  hardly  more  than 
0.000002  %  if  the  oils  treated  were  entirely  neutral. 

«*  GARTH,  Seif.  Zeit.,  39,  1277  (1912). 

43  According  to  information  obtained  from  DR.  WESSON,  hydrogenation  is  carried 
on  in  the  United  States  by  about  60  concerns  and  hydrogenated  oils  are  impor- 
tant constituents  in  some  92  brands  of  shortening.  Formerly  these  were  regarded 
as  lard  substitutes  but  they  have  made  an  independent  position  for  themselves  as 
"vegetable  shortening"  and  have  found  favor  with  many  who  object  to  lard. 

For  edible  products  cottonseed  oil  is  the  chief  oil  that  is  hydrogenated.  The 
aim  is  to  prepare  a  product  that  will  not  be  too  hard  in  winter  or  too  soft  in  summer. 
Sometimes  the  whole  of  the  oil  is  hydrogenated.  The  chief  products  thus  made 


CATALYSIS  IN  ORGANIC  CHEMISTRY  350 

for  the  American  market  are  Crisco,  Selex,  MFB,  and  Fairco.  These  melt  at  33 
to  37°  and  have  iodine  numbers  running  from  76  to  86.  By  varying  the  mode  of  hy- 
drogenation,  products  with  nearly  the  same  melting  points  but  with  iodine  numbers 
varying  as  much  as  10  points  may  be  obtained. 

By  hydrogenating  down  to  an  iodine  number  of  10  to  20  and  mixing  this  very 
hard  fat  with  untreated  cottonseed  oil  the  desired  consistency  may  be  obtained  with 
a  much  higher  average  iodine  number.  This  is  the  most  common  practice  as  much 
less  hydrogen  is  required  and  the  fraction  of  the  oil  that  has  to  be  hydrogenated  is 
small. 

The  melting  points  and  iodine  numbers  of  some  leading  brands  are  as  follows: 

Melting  Point        Iodine  Number 

Scoco 44.4  89.2 

Snowdrift 44.1  89.3 

Armstrong  White  Cloud 45.8  99.4 

Armstrong  Bob  White 39.2  93.5 

Fairbanks  Boar's  head 41.8  100 

Morris  Purity 42.0  97.5 

P.  and  G.  Flake  white 42.8  90.6 

P.  and  G.  White  flake 47.8  87.4 

Swift  Jewel 45.5  97.0 

Wilson  Advance 44.2  96.9 

Kream  Krisp 45.5  97.0 

Highly  hydrogenated  cottonseed  oil  is  a  hard,  white,  brittle  solid  and  does  not 
become  rancid.  These  properties  make  it  a  suitable  constituent  for  prepared  cake 
flours. 

Vast  amounts  of  fish  oils  are  hydrogenated  to  be  used  in  making  soaps. 

E.  E.  R. 


AUTHOR  INDEX 

(References  are  to  Paragraphs:  a  number  followed  by  "n"  designates  a  note.) 


Abakumobskaya,    Miss    L.    N.,    with 

Nametkin,  478 
Aboulenc,  Jean,   with  Senderens,   598, 

758,  759,  760 

Acree,  S.  F.,  and  Johnson,  J.  M.,  202 
Adam,  Paul,  241,  896 
Adams,  Roger;  Kamm,  O.,  and  Marvel, 

C.  S.,  306,  696,  713 
Adkins,  Homer,  797n,  861n 
Ador,  E.,  with  Rilliet,  291 
Adrianowsky,  297 
Akunoff,  J.,  with  Lunge,  445 
Alexyef ,  899 

Allen,  William,  and  Kolliker,  Alfred,  890 
Almedingen,  212 
Aloy,  J.,  and  Brustier,  385,  661 
Altmayer  with  Mayer,  411 
Amberger,  C.,  with  Paal,  69,  70,  545 
Ambrey,  A.,  with  Bourquelot,  18 
Amouroux,  G.,  385,  435 
Amouroux,  G.,  with  Mailhe,  739 
Amouroux,  G.,  with  Murat,  414,  415 
Andrews,  C.  E.,  with  Boehner,  811 
Anschiitz,  Richard,  885,  889,  897 
Anschutz,  R.,  and  Immendorff,  H.,  888 
Antropoff,  A.  von,  180a 
Antropoff,  A.  von,  with  Bredig,  180a 
Arbusof,  A.  E.,  and  Friauf,  A.  P.,  633 
Arbusof,  A.  E.,  and  Khrutzkii,  N.  E.,  633 
Arbusof,  A.  E.,  and  Tichwinsky,  W.  M., 

611,  633,  635 

Armstrong,  H.  E.,  and  Tilden,  W.  A.,  198 
Aronheim,  B.,  286 
Arrhenius,  Svante,  178,  319,  324 
Asahina,  Y.,  571 
Aschan,  Ossian,  929 
Atkinson,  R.  H.,  Heycock,  C.  T.,  and 

Pope,  W.  J.,  282n 
Auger,  Victor,  893 
Auger,  V.,  and  Behal,  A.,  280 
Austerweil,  Geza,  260n 


Baborovsky,  G.,  and  Kuzma,  B.,  276 
Badische,  A.  S.  Fb.,  180s,  215,  270,  273, 

511,  730,  876 
Baekeland,  Leo  H.,  792 
Baeyer,  Adolf,  90,  893 
Baeyer,  Adolf,  and  Drewsen,  Viggo,  798 
Baker,  H.  B.,  73 

Baly,  E.  C.  C.,  and  Krulla,  Rudolf,  180 
Bancroft,  W.  D.,  116n,  180a,  1800,  180s 
Barbaglia,  G.  A.,  224 
Barbier,  Ph.,  and  Locquin,  R.,  565 
Bardt,  A.  Y.,  with  Doroshevskii,  268, 

275 

Barendrecht,  H.  P.,  ISOj 
Bartels,  A.,  with  Jannasch,  817 
Bartels,  G.,  with  Meigen,  598 
Bauer,  A.,  211 

Bauer,  Maurice,  with  Brochet,  601 
Baumann,  E.,  150,  233 
Bayer,  A.  G.,  232 
Bayer  and  Co.,  104,  298 
Bayley,  180a 

Becker,  C.,  with  Semmler,  570 
Beckmann,  E.,  185,  189 
Bedford,  Fred,  939 

Bedford,  F.,  and  Erdmann,  E.,  598,  943 
Bedford,  F.,  and  Williams,  C,  E.,  939, 

941,  943 

B6hal,  A.,  192,  308 
B6hal,  A.,  with  Auger,  280 
Behn,  Richard,  892 
Beilstein,  F.,  and  Geitner,  P.,  278 
Beilstein,  F.,  and  Kuhlberg,  A.,  287 
Belloni,  E.,  with  Carrasco,  250 
Bergen,  J.  von,  with  Skita,  554 
Bergius,  Friedrich,  954 
Bergreen,  Henry,  894 
Berl,  E.,  180r 
Berliner,  1800 
Bernthsen,  August,  296 
Berthelot,  Marcellin,  21, 60,  84,  148, 165, 


351 


352 


AUTHOR  INDEX 


160,  1800,  308,  325,  340,  409,  477,  616, 

637,  650,  749,  750n,  751,  752,  757,  758, 

767,  768,  770,  822,  905,  909,  914,  926 
Berthelot  and  Jungfleisch,  650,  749 
Berthelot  and  St.  Gilles,  758n 
Bertrand,  Gab.,  153,  264 
Berzelius,  J.,  4,  129 
Bevan,  E.  J.,  with  Cross,  268 
Bialobizeski,  M.,  900 
Biehler,  F.,  with  Paal,  70 
Blackadder,  Thomas,  822 
Blaise,  304 

Blanck,  F.  C.,  with  Tingle,  269n 
Blanes,  J.  S.,  with  Madinaveitia,  569, 

577 

Blanksma,  J.  J.,  with  van  Ekenstein,  186 
Bodenstein,  Max,  8 
Bodenstein,  Max,  and  Fink,  Colin  G., 

180r 

Bodlander,  G.,  Koppen,  K,  180r 
Bodroux,  F.,  751,  752,  757 
Bodroux,  F.,  and  Taboury,  F.,  420 
Boedtker,  Eyrind,  819 
Boedtker,  Eyrind,  and  Halse,  O.  M.,  888 
Boehner,  R.  S.,  and  Andrews,  C.  E.,  811 
Boehner,  R.  S.,  and  Ward,  A.  L.,  811 
Boeseken,  J.,  81,  87,  224,  643 
Boeseken,  J.,  and  Schimmel,  A.,  224 
Boeseken,  J.,  van  der  Scheer,  J.,  and  de 

Vogt,  J.  G.,  879 

Boeseken,  J.,  and  van  Senden,  G.  H.,  664 
Boeseken,  J.,  van  de  Weide,  O.  B.,  and 

Mom,  C.  P.,  117,  546 
Boessneck,  P.,  89 
Boettger,  B.,  62,  165 
Bone,  W.  A.,  and  Jerdan,  D.  S.,  409 
Bornwater,  J.  T.,  and  Holleman,  A.  F., 

284 

Borodin,  A.,  795 

Borsche,  W.,  and  Heimbiirger,  G.,  546 
Borsche,  W.,  and  Wollemann,  J.,  546 
Bosler,  M.,  220 

Boters,  O.,  with  Wolffenstein,  269 
Bouchardat,  G.,  212 
Boudet,  F.,  184 
Boudouard,  O.,  615 
Bougault,  J.,  203 
Boullay,  J.  F.  G.,  691 
Bourquelot,  Em.,  and  Aubry,  A.,  18 
Bouveault,  L.,  654,  656,  663,  717 
Bouveault,  L.,  and  Locquin,  Rene",  663 


Boyd,  Robert,  with  Henderson,  459 
Braun,  J.  von,  and  Deutsch,  H.,  897 
Braune,  H.,  12 
Bredig,  G.,  68 

Bredig,  G.,  and  V.  Antropff,  180a 
Bredig,  G.,  and  Brown,  John  Wesley,  272 
Bredig,  G.,  and  Carter,  S.  R.,  574 
Bredig,  G.,  and  Fraenkel,  W.,  12 
Bredig,  G.,  and  Ikeda,  K.,  116 
Bredig,  G.,  and  Joyner,  R.  A.,  836 
Breteau,  Pierre,  484,  536,  562,  571,  579 
Breuer,  Aug.,  and  Zincke,  Th.,  220 
Brochet,  Andre",  30,  596,  598,  599,  600, 

603 

Brochet,  Andre",  and  Bauer,  Maurice,  601 
Brochet,   Andre",  and  Cabaret,  Andre", 

601,  602 

Bromberg,  O.,  with  Fischer,  187 
Brooks,  Benj.  T.,  and  Humphrey,  Irwin, 

210,  306 

Brown,  J.  W.,  with  Bredig,  272 
Brown,  O.  W.,  and  Carrick,  L.  L.,  512 
Bruce,  James,  with  Willstatter,  293,  473 
Brunei,  L.,  126,  349,  443,  459,  464 
Bruner,  L.,  291 
Brunner,  W.,  with  Skita,  561 
Brustier,  V.,  with  Aloy,  385 
Bugarszky,  Stefan,  178 
Bum,  Friedrich,  with  Kohn,  293 
Bunsen,  R.,  180r 
Burrows,  George  J.,  324 
Burstert,  H.,  with  Glaus,  285 
Burstyn,  Walther,  234 
Butlerow,  A.,  210,  306 

Cabaret,  Andre",  with  Brochet,  601,  602 

Caldwell,  G.  C.,  and  Grossmann,  A.,  184 

Calm,  A.,  89 

Calvert,  F.  C.,  48,  1806 

Cannizzaro,  S.,  880 

Carpenter,  C.  C.,  372 

Carrasco,  O.,  and  Belloni,  E.,  250 

Carrasco,  O.,  and  Padoa,  M.,  497,  684 

Carrick,  L.  L.,  with  Brown,  512 

Carter,  S.  R.,  with  Bredig,  574 

Carughia,  A.,  with  Padoa,  489 

Cathcart,  W.  R.,  Jr.,  and  Meyer,  Victor, 

893 

Chauvin,  A.  C.,  268 
Chelintzev,  V.  V.,  and  Trunov,  B.  V., 

805 


AUTHOR  INDEX 


353 


Ch.  Fab.  auf  Actien  (E.  Sobering),  215 
Chem.  Fabr.  Buckau,  881 
Chiaves,  C.,  with  Padoa,  490 
Chichibabin,  A.  E.,  310,  686,  807,  810 
Chichibabin,    A.    E.,    and    Ryumshin, 

P.  F.,  901 

Chowdhuri,  T.  C.,  with  Neogi,  382 
Ciamician,  G.,  647 
Ciamician,  G.,  and  Silber,  P.,  150 
Claisen,  L.,  783,  799,  804 
Claisen,  L.,  and  Claparede,  A.,  798 
Claisen,  L.,  and  Crismer,  L.,  106 
Claisen,  L.,  and  Ponder,  A.  C.,  798 
Claparede,  with  Claisen,  L.,  798 
Clark,  Latham,  and  Jones,  W.  N.,  414 
Glaus,  Ad.,  207,  893 
Glaus,  Ad.,  and  Burstert,  H.,  285 
Clement  and  Desormes,  324 
Cohen,  Ernest,  8 
Cohen,  J.  B.,  and  Dakin,   Henry,   D., 

293 

Cohen,  Lillian,  with  Harding,  298 
Colin,  H.,  and  S&ie"chal,  A.,  11 
Colson,  Albert,  858 
Commercial  Research  Co.,  269n 
Consortium  /.  Electroch.  Ind.,  228 
Cooke,  Stephen,  166 
Copisarow,  Maurice,  893 
Corenwinder,  B.,  15,  342 
Cornubert,  R.,  602 
Couroy,  James  T.,  161,  837 
Crafts,  J.  M.,  82 
Crafts,  J.  M.,  with  Friedel,  87,  173,  263, 

295,  297,  883,  889,  890,  893 
Crismer,  L.,  with  Claisen,  106 
Cross,  C.,  F.,  Bevan,  E.  J.,  and  Heiberg, 

Th.,  268 
Crossfield,   J.,   and  Sons,  and  Markel, 

K.  E.,  941 
Curtius,  Th.,  and  Foersterling,  H.  A., 

196 

Curtius,  Th.,  and  Lang,  J.,  332 
Cusmano,  Guido,  564,  571 

Dakin,  H.  D.,  with  Cohen,  293 

Damoiseau,  O.,  48,  1806,  282 

Daniels,   E.  A.,  with  Frankforter,  239, 

806 
Darzens,  Georges,  30,  56,  243,  360,  389, 

417,  420,  476,  488  MJgMMjp 

Darzens,  G.,  and  Rost,  H.,  390,  459,  476 


Davy,  E.,  4 

Davy,  Sir  Humphrey,  4 

Day,  D.  T.,  946 

Deacon,  H.,  103,  180r 

Debray,  H.,  with  St.  Claire-Deville,  64, 

822 

Debus,  Heinrich,  180d,  ISO/,  342,  528 
Delepine,  Marcel,  795 
Delisle,  Alfred,  183 
Demole,  E.,  890 
Demtschenko,  S.,  224 
Demuth,  R.,  and  Dittrich,  M.,  893 
Deniges,  Georges,  268 
Dennstedt,  M.,  742 
Dennstedt,  M.,  and  Hassler,  F.,  257 
Desormes,  with  Clement,  324 
Deutsch,  H.,  with  v.  Braun,  897 
Deuss,  J.  J.  B.,  629 
Deussen,  Ernst,  560 
Deville,  St.  Glair,  346 
Dewar,  James,  132,  136,  165 
Dey,  M.  L.,  with  Ray,  815n 
Dimroth,  Otto,  and  W.  von  Schmaedel, 

816 

Dittrich,  M.,  with  Demuth,  893 
Ditz,  Hugo,  272 
Dixon,  Harold  B.,  73 
Doebereiner,  J.  W.,  62 
Doroshevskii,  A.  G.,  and  Bardt,  A.  Y.t 

268,  275 

Douris,  Roger,  208,  419 
Dovgelevich,  N.,  with  Ipatief,  920 
Downes,  Helen  R.,  with  Reimer,  340n 
Downs,  C.  R.,  with  Weiss,  260n 
Drachussow,  with  Ipatief,  594 
Drewsen,  Viggo,  with  Baeyer,  798 
Dreyfus,  Henri,  255,  261,  309 
Douris,  Roger,  487 
Dubois,  H.,  with  Miiller,  A.,  285 
Dubrumfaut,  188 
Ducelliez,  F.,  Gay,  L.,  and  Raynaud,  A.f 

292 

Duclaux,  Jacques,  139 
Dulk,  L.,  with  Meyer,  224 
Dulong,  and  ThSnard,  637 
Dumas,  J.,  and  Peligot,  E.,  691 
Dupont,  Georges,  195.  565,  577 

Earle,  R.  B.,  and  Kyriakides,  L.  P.,  to 

Hood  Rubber  Co.,  802 
Earle,  R.  B.,  with  Kyriakides,  723 


354 


AUTHOR  INDEX 


Easterfield,   T.   H.,   and  Taylor,   Miss 

Clara,  M.,  843 
Egloff,  Gustav,  and  Moore,  Robert  J., 

909 

Egloff,  Gustav,  and  Twomey,  T.  J.,  908 
Egloff,  Gustav,  with  Zanetti,  907 
Eijkman,  J.  F.,  392,  452,  454,  474 
Ekl,  Elizabeth,  with  Klemenc,  269n 
Elbs,  Karl,  605 
Ellis,  Carleton,  941,  962 
Ellis,  C.,  and  Rabinovitz,  Louis,  601 
Ellis,  C.,  and  Wells,  A.  A.,  949 
Engel,  R.,  and  de  Girard,  780 
Engelder,  C.  J.,  1080,  694,  708,  710 
Engler,  C.,  150 
Engler,  C.,  and  Wild,  W.,  150 
Engler,  C.,  and  Wohler,  Lothar,  137,  154 
Enklaar,  C.  J.,  415,  416 
Erdmann,  E.  O.,  188,  598,  754,  941,  958 
Erdmann,  E.,  with  Bedford,  598,  943 
Erdmann,  E.,  and  Rack,  E.,  944 
Erlenmeyer,  Emil,  321,  696 
Erlenmeyer,  E.  Jr.,  203 
Espil,  Le*o,  with  Sabatier,  12,  16,  56,  80, 

113,  114,  125;  338,  346,  358,  492,  598 
Euler,  A.,  with  Euler,  H.,  225 
Euler,  Hans,  324 
Euler,  H.,  and  Euler,  A.,  225 
Evans,  E.  V.,  372 
Evans,  P.  N.,  and  Sutton,  Lena  M.,  691 

Fabinyi,  R.,  90 

Fabris,  Ugo,  with  Padoa,  484,  491,  642, 

643 

Fahlberg,  List  and  Co.,  285 
Faillebin,  with  Vavon,  565 
Fajans,  Kasimir,  836 
Faraday,  Michael,  180o 
Farbw.  Meister,  Lucius,  and  Bruning, 

378 

Farbf.,  v.  F.  Bayer  and  Co.,  816 
Fassek,  W.,  795 

Farre,  P.  A.,  and  Silbermann,  J.  T.,  131 
Faworsky,  AL,  192 
Fenton,  H.  J.  H.,  268 
Fenton,  H.  J.  H.,  and  Jackson,  Henry, 

268 

Fenton,  H.  J.  H.,  and  Jones,  H.  O.,  268 
Filippov,  O.  G.,  577 
Filippov,  O.  G.,  with  Ipatief,  589,  590 
Fink,  C.  G.,  with  Bodenstine,  180r 


Fischer,  Emil,  81, 187,  220,  754,  756,  758 
Fischer,  E.,  and  Bromberg,  O.,  187 
Fischer,  Emil,  and  Fischer,  O.,  890 
Fischer,  E.,  and  Giebe,  Georg,  782 
Fischer,   E.,   and   von   Mechel,  Lucas, 

793 

Fischer,  E.,  and  Morell,  R.  S.,  187 
Fischer,  E.,  and  Passmore,  F.,  221 
Fischer,  E.,  and  Piloty,  O.,  187 
Fischer,  E.,  and  Speier,  Arthur,  753 
Fischer,  E.,  and  Tafel,  J.,  237 
Fischer,  Ernst,  with  Schmidt,  571 
Fischer,  Franz,  931 

Fischer,  Franz,  and  Niggemann,  Her- 
mann 930 

Fischer,  O.,  with  Fischer,  E.,  890 
Fischer,  O.,  and  Korner,  G.,  89 
Fittig,  Rudolph,  11,  183,  203,  293,  797 
Fittig,  R.,  and  Kohl,  Wilhelm,  183 
Fittig,  R.,  and  Langworthy,  C.,  F.,  183 
Fleitmann,  Th.,  270 
Foesterling,  H.  A.,  with  Curtius,  196 
Fokin,  S.,  12,  252,  254,  266,  526,  556, 

562,  587 

Formin,  W.,  with  Tchougaeff,  570 
Fossek,  W.,  224 
Fournier,  H.,  567 
Fownes,  G.,  194 
Fraenkel,  W.,  with  Bredig,  12 
Franchimont,  A.  P.  N.,  761 
Franke,  Adolf,  226 

Franke,  Adolf,  and  Kohn,  Leopold,  234 
Franke,  Adolf,  and  Kohn,  Moritz,  227 
Franke,  Adolf,  and  Wozelka,  Hermann, 

223 
Frankfort er,  G.  B.,  and  Daniels,  E.  A., 

239,  806 
Frankforter,  G.  B.,  and  Kokatnur,  V.  R., 

806 
Frankforter,   G.   B.,  and  Kritchevsky, 

W.,  806 

Frankland,  E.,  and  Kolbe,  H.,  232 
Freas,  Raymond,  and  Reid,  E.  Emmet, 

758n 

Fre"bault,  A.,  428 
Frerichs,  G.,  598 

Freund,  Michael,  with  Sleinkopf,  931 
Friauf,  A.  P.,  with  Arbuzof,  633 
Friedel,  C.,  and  Crafts,  J.  M.,  87,  173, 

263,  295,  297,  883,  889,  890,  893 
Friedmann,  T.  E.,  with  Huston,  728 


AUTHOR  INDEX 


355 


Gabriel,  S.,  and  Neumann,  A.,  107 

Gambler,  with  Trillat,  781 

Gangloff,  W.  C.,  and  Henderson,  W.  E., 

899 

Garrand,  S.  F.,  with  Weismann,  654n 
Garth,  Johann,  967 
Gattermann,  Ludwig,  606,  610,  895 
Gattermann,  L.,  with  Stockhausen,  886 
Gattermann,  L.,  and  Koch,  J.  A.,  298 
Gaudion,  Georges,  382,  429,  513,  741 
Gaudion,  Georges,  with  Sabatier,  631, 

634,    641,    643,   644,    6*5,  680,    681, 

726,  923 

Gay,  L.,  with  Ducelliez,  292 
Geigy,  R.,  and  Koenigs,  W.,  893 
Geilmann,  W.,  with  Mannich,  656 
Geitner,  P.,  with  Beilstein,  278 
Genieser,  Ad.,  with  Wilgerodt,  238 
Genveresse,  P.,  890 
Gerum,  J.,  576 

Gerum,  J.,  with  Paal,  72,  546,  556 
Geuther,  A.,  387,  780 
Gibbs,  H.  D.,  244n,  249n,  254n,  257n, 

260n,  262w,  273n 
Gibello,  with  Seyewetz,  221 
Giebe,  Georg,  with  Fischer,  782 
Girard,  de,  with  Engel,  780 
Gladstone,  J.  H.,  and  Tribe,  Alfred,  165, 

166,  169,  785 

Glinka,  N.,  with  Zelinski,  648,  822 
Godchot,    Marcel,   29,   363,   390,   392, 

453,  482,  483 
Godchot,  Marcel,  and  Taboury,  Fe*lix, 

390,  421,  436,  856 
Godon,  F.  de,  with  Mailhe,  539,  682, 

740,  772n,  808,  814 
Godon,  F.  de,  with  Sabatier,  801 
Goldberg,  Irma,  901 
Goldschrnidt,    Heinrich,    and    Larsen, 

Halfdan,  283,  288 
Goldsmith,  J.  N.,  661 
Gossmann,  A.,  with  Caldwell,  184 
Gottlieb,  J.,  183 

Gottlob,  Kurt,  with  Harries,  235 
Graebe,  C.,  272 

Graebe,  C.,  and  Guye,  Ph.,  107 
Graebe,  C.,  Liebermann,  C.,  328 
Graham,  Thomas,  65,  536 
Grassi,  G.,  496 

Greene,  W.  H.,  with  LeBel,  691 
Griesheiin  Elektron,  with  Johnson,  260 


Grignard,  Victor,  11,  104 

Grigoreff,  702 

Grillet,  339 

Grimaux,  fidouard,  246,  680 

Gross,  K.  F.  L.,  215 

Grube,  G.,  and  Kriiger,  J.,  233 

Gruearevic,  S.,  and  Merz,  V.,  899 

Grim,  A.,   with  G.  Schicht,  Akt.-Ges., 

846 

Gustavson,  G.,  174,  199,  290,  293 
Guthrie,  F.,  691 
Guttmann,  O.,  with  Stock,  8 
Guye,  Ph.,  with  Graebe,  107 
Guyot,  A.,  with  Haller,  893 

Haag,  J.,  233 

Haarmann,  Wilh.,  with  Tiemann,  329 

Hall,  W.  A.,  933 

Haller,  A.,  334,  341 

Haller,  A.,  and  Guyot,  A.,  893 

Haller,  A.,  and  Lassieur,  A.,  435 

Haller,  A.,  and  Martine,  C.,  416,  421, 

436,  476,  478 

Haller  and  Youssouffian,  341 
Halse,  O.  M.,  569 
Halse,  O.  M.,  with  Boedtker,  888 
Hamonet,  J.,  902 
Hantzsch,  A.,  893 
Harbeck,  E.,  and  Lunge,  G.,  180o 
Harding,    E.   P.,   and    Cohen,  Lillian, 

298 

Earned,  Herbert,  S.,  180g 
Harries,  C.,  213 

Harries,  C.,  and  Gottlob,  Kurt,  235 
Hartmann,  Wilhelm,  with  Paal,  1800 
Hartwich,  Frank,  with  Wolffenstein,  893 
Hassler,  F.,  with  Dennstedt,  257 
Hatt,  Daniel,  with  Willstatter,  569,  571 
Hauser,  O.,  and  Klotz,  A.,  778 
Haussknecht,  Otto,  184 
Hautefeuille,  P.,  15 
Heckel,  W.,  with  Knoevenagel,  650,  669, 

692,  720 

Heidelberger,  M.,  with  Willstatter,  571 
Heilberg,  Th.,  with  Cross,  268 
Heimbiirger,  G.,  with  Borsche,  546 
Heinemann,  A.,  815 

Helfrich,  O.  B.,  and  Reid,  E.  E.,  278n 
Heller,  Gustav,  and  Schulke,  Kurt,  889n, 

898 
Hemptinne,  A.  de,  1800 


356 


AUTHOR  INDEX 


Henderson,  G.  G.,  and  Boyd,  Robert, 

459 
Henderson,    G.    G.,    and    Sutherland, 

Maggie  M.,  463 

Henderson,  W.  E.,  with  Gangloff,  899 
Henrard,  J.  Th.,  418 
Henri,  Victor,  180;,  180r 
Henry,  L.,  236 
Henseling,  410 

Herzenstein,  Anna,  with  Zelinski,  649 
Hess,  K.,  and  Liebbrandt,  F.,  561 
Heycock,  C.  T.,  with  Pope,  282n 
Hibbert,  Harold,  699 
Higgins,  E.  B.,  944 
Higgins,  E.  B.,  with  Wimmer,  944 
Hobohm,  K.,  with  Vorlander,  799 
Hoffmann,  F.,  and  La  Roche  and  Co.,  555 
Hofmann,  A.  W.,  63,  232,  287 
Hofmann,  K.  A.,  262 
Hofmann,  K.  A.,  and  Schibsted,  Helge, 

824 

Hofmann,  K.  A.,  and  Schumpelt,  K.,  271 
Hohenegger,  C.,  with  Paal,  212,  548 
Holdermann,  K.,  269n 
Holleman,  A.  F.,  with  Bornwater,  284 
Holtzwart,  Rudolf,  231 
Hood  Rubber  Co.,  with  Earle,  802 
Hoppe,  Eduard,  795 
Hoppe-Seyler,  F.,  150 
Houben,  J.,  and  Pfau,  A.,  569 
Hiibl,  Baron,  938 
Hiibner,  H.,  and  Majest,  W.,  278 
Hufner,  G.,  ISOd 
Hugershoff,  A.,  630 
Humphrey,  Irwin,  210,  306 
Husemann,  Aug.,  and  Marme*,  Wilh.,  330 
Huston,  R.  C.,  and  Friedmann,  T.  E., 

728 
Hutin,  Albert,  792 

Ikeda,  K.,  with  Bredig,  116 
Iljinsky,  M.,  816 

Immendorff,  H.,  with  Anschiitz,  888 
Imray,  O.,  from  Fbw.  Meister,  Lucius 

and  Bruning,  228 
Ingle,  Harry,  with  Mackey,  266 
Ipatief,  Vladimir  N.,  78,   1800,   180r, 
190,  211,  232,  542,  543,  584,  585,  586, 
587,  588,  589,  590,  591,  592,  593,  594, 
595,  598,  667,  670,  694,  702,  706,  711, 
714,  717,  722,  724,  943 


Ipatief  and  Dovgelevich,  N.,  920 

Ipatief  and  Drachussow,  594 

Ipatief,  V.,  Jakowlew,  W.,  and  Rakitin, 

W.,  592 

Ipatief  and  Leontowitch,  W.,  200 
Ipatief  and  Louvogoi,  589 
Ipatief,  V.,  and  Matow,  N.,  591,  722 
Ipatief,  V.,  and  Filippov,  O.,  589,  590 
Ipatief,  V.,  and  Rutala,  O.,  211,  714 
Ipatief,  V.,  and  Schulman,  G.  G.,  838 
Ipatief,  V.,  and  Sdzitowecky,  W.,  713 
Ittner,  Martin  H.,  54n,  941n 

Jackson,  Henry,  with  Fenton,  268 

Jacobson,  Oscar,  291,  887 

Jacquet,  D.,  with  Willstatter,  563,  569 

Jahn,  Hans,  678 

Jakowlew,  W.,  with  Ipatief,  592 

Jannasch,  P.,  and  Bartels,  A.,  817 

Jennings,  H.  S.,  12 In 

Jerdan,  D.  S.,  with  Bone,  409 

Joannis,  J.,  267 

Job,  Andre*,  153 

Johnson,  F.  M.  G.,  1800 

Johnson,  G.  W.,  from  Griesheim  Elek., 

260 

Johnson,  J.  M.,  with  Acree,  202 
Jonas,  K.  G.,  with  Semmler,  570 
Jones,  H.  O.,  with  Fenton,  268 
Jones,  W.  N.,  with  Clark,  414 
Jorissen,  W.  P.,  and  Reicher,  L.  Th.,  100 
Joyner,  R.  A.,  with  Bredig,  836 
Jungfleisch,  fimile,  278 
Jungfleisch,  with  Berthelot,  650,  749 

Kametka,  T.,  with  Willstatter,  197,  472, 

479 
Kamm,  O.,  with  Adams,  and  Marvel, 

306,  696,  713 
Kastle,  J.  H.,  and  Loevenhart,  A.  S., 

180s 

Kaschirski,  M.,  200 
Kawalier,  A.,  328 
Kayser,  E.  C.,  941,  963 
Keghel,  Maurice  de,  481n 
Keiser,  E.  H.,  with  Remsen,  150 
Kekule',  Aug.,  182,  183,  795,  796 
Kekuld,  A.,  and  Schrotter,  H.,  199 
Kekule",  A.,  and  Strecker,  Otto,  182 
Kekule",  A.,  and  Zincke,  Th.,  222 


AUTHOR  INDEX 


357 


Kelbasinski,  S.  S.,  with  Ostromuisslen- 

skii,  784 

Kelber,  C.,  598,  599 
Kelber,  C.,  and  Schwartz,  A.,  69,  548 
Kempf,  R.,  276 

Kenner,  James,  with  Knoevenagel,  297 
Kerez,  Conrad,  877 
Khrutzkii,  N.  E.,  with  Arbuzof,  633 
Kimura,  Kanesuke,  964 
Kipping,  F.  Stanley,  799 
Kijner,  N.,  444 

King,  A.  T.,  and  Mason,  F.  A.,  782 
King,  V.  L.,  with  Willstatter,  569,  571 
Kjeldahl,  272 
Kirchof,  4 

Kizhner,  N.,  611,  612 
Klemenc,   Alfons,   and  Ekl,  Elizabeth, 

269n 

Klever,  H.  W.,  with  Staudinger,  235 
Klotz,  A,  with  Hauser,  778 
Kluge,  Paul,  278 
Knoevenagel,   E.,  240,   296,   632,   729, 

790,  804 
Knoevenagel,  E.,  and  Heckel,  W.,  650, 

669,  692,  720 

Knoevenagel,  E.,  and  Kenner,  J.,  297 
Koch,  Erwin,  278 
Koch,  J.  A. ,  with  Gattermann,  298 
Koelichen,  Karl,  229 
Koenigs,  W.,  with  Geigy,  893 
Koerner,  G.,  and  Menozzi,  A.,  312 
Kohl,  Wilhelm,  with  Fittig,  183 
Kohn,  Leopold,  with  Franke,  234 
Kohn,  Moritz,  697 
Kohn,  Moritz,  with  Franke,  227 
Kohn,  Moritz,  and  Bum,  Friedrich,  293 
Kohn,  M.,  and  Miiller,  N.  L.,  293 
Kokatnur,  V.  R.,  with  Frankforter,  806 
Kolbe,  H.,  with  Frankland,  232 
Kolbe,  H.,  and  Saytzeff,  Michael,  165, 

536 

Kolliker,  Alfred,  with  Allen,  890 
Konsortium    f.    Elektrochemische    In- 
dustrie, 228 

Kopp,  Adolph,  with  Michael,  219 
Koppen,  K,  with  Bodlander,  180r 
Korner,  G.,  with  O.  Fischer,  89 
Koshelev,  F.  F.,  with  Ostromuislenskii, 

214 

Kotz,  A.,  and  Schaeffer,  550 
Koursanof,  N.  J.,  889 


Kramer,  G.,  and  Spilker,  A.,  217 
Kramer,  R.  L.,  and  Reid,  E.  E.,  707n, 

708n,  744n 

4015    Catalysis   8-8-10   JM    18  gal  6 
Krassuski,  K.,  200 
Kraut,  K.,  329 

Krestinsky,  V.,  and  Nikitine,  N.,  713 
Kritchevsky,  W.,  with  Frankforter,  806 
Kriiger,  A.,  278 
Kriiger,  F.,  180; 
Kriiger,  J.,  with  Grube,  233 
Kriiger,  Paul,  with  Tiemann,  198,  800 
Krulla,  Rudolf,  with  Baly,  180i 
Kuhlberg,  A.,  with  Bielstein,  287 
Kuhlmann,  F.,  342,  529 
Kutscheroff,  M.,  309 
Kuzma,  B.,  with  Babarovsky,  276 
Kuznetzosr,  M.  I.,  623,  920 
Kvapishevskii,    K.  V.,    with   ZaTkind, 

548,  566 

Kyriakides,  L.  P.,  726 
Kyriakides,  L.  P.,  and  Earle,  R.  B.,  723, 

802 

Lafont,  J.,  216 

Laming,  146 

Landolph,  F.,  211 

Lang,  J.,  with  Curtius,  332 

Langer,  C.,  with  Mond,  614 

Langmuir,  Irving,  180rf,  180e,  180/,  180p 

Langworthy,  C.  F.,  with  Fittig,  183 

Larsen,  Halfdan,  with  Goldschmidt,  283, 

288 

Lassieur,  A.,  435 
Lassieur,  A.,  with  Haller,  435 
Laurent,  A.,  184 
Lazarew,  293 
Lebach,  H.,  792 
Le  Bel  and  Greene,  W.  H.,  691 
Le  Chatelier,  131 
Leeds,  Albert  R.,  150 
Lehmann,  F.,  583 
Lemonie,  Georges,  2,  11,  20,  32,  34,  38, 

49,  63,  77,  679 

Leontowitch,  W.,  with  Ipatief,  200 
Leprince,  and  Siveke,  542 
Lerczynska,  Miss  I.,  with  Pictet,  936 
Leroux,  Henri,  481 
Leroy,  A.  J.,  293 

Lescoeur,  H.,  and  Rigaut,  A.,  230 
Lespieau,  R.,  566 


358 


AUTHOR  INDEX 


Lespieau,  R.,  and  Vavon,  G.,  566 

Lewis,  W.  C.  McC.,  180;,  180r 

Lewkowitsch,  314,  318 

Libavius,  4 

Lieben,  Adolf,  104,  222,  321,  795 

Liebermann,  C.,  with  Graebe,  328 

Liebig,  Justus  von,  11,  312 

Liebig,  Justus  von,  with  Wohler,  220 

Liebrandt,  F.,  with  Hess,  561 

Limpricht,  H.,  278,  320,  851 

Lindenbaum,    Ernst,    with    Naumann, 

260,  269 

Lineburger,  C.  E.,  890 
Lipp,  Peter,  478 

Lippmann,  Edmund  0.  von,  324 
Livache,  Ach.,  266 
Lobry  de  Bruyn,  C.  A.,  186 
Locquin,  R.,  with  Barbier,  565 
Locquin,  Rene",  with  Bouevault,  663 
Loevenhart,  A.  S.,  with  Kastle,  180s 
Loew,  O.,  62,  221,  562,  621 
Longman,  J.,  298 
Lorin,  822 
Louise,  E.,  797 
Louvogoi,  with  Ipatief,  589 
Lowenherz,  Richard,  315 
Lucas,  O.  D.,  with  Valpey,  933 
Ludwig,  H.,  329 
Lunge,  G.,  and  Akunoff,  J.,  445 
Lunge,  G.,  with  Harbeck,  1800 

McAfee,  A.  M.,  935 

Mackey,  W.  McD.,  and  Ingle,  Harry, 
266 

Madinaveitia,  A.,  117,  580 

Madinaveitia,  A.,  and  Blanes,  J.  S.,  569, 
577 

Mahl,  with  Wohler,  75 

Mailhe,  Alphonse,  383,  386,  435,  514, 
735,  745,  833,  842,  843,  849 

Mailhe,  Alphonse,  with  Sabatier,  75,  77, 
78,  112,  127,  162,  169,  170,  258,  337, 
343,  347,  363,  385,  387,  391,  404,  406, 
407,  420,  422,  430,  431,  437,  438,  442, 
457,  458,  461,  470,  475,  486,  495,  521, 
617,  621,  628,  641,  651,  655,  660,  672, 
673,  674,  677,  689,  693,  702,  704,  706, 
708,  709,  714,  715,  717,  731,  733,  734, 
735,  737,  739,  743,  744,  745,  746,  762, 
766,  769,  771,  772,  774,  777,  785,  786, 
787,  788,  789,  791,  794,  822,  823,  824, 


834,  839,  842,  843,  844,  845,  849,  850, 

852,  853,  856,  857,  858,  866,  873,  876, 

878,  916,  923 

Mailhe,  A.,  and  Amouroux,  739 
Mailhe,  Alph.,  and  de  Godon,  F.,  539, 

682,  740,  772n,  808,  814 
Mailhe,  A.,  and  Murat,  Marcel,  384, 

385,  494 

Majest,  W.,  with  Hiibner,  278 
Mamontoff,  W.,  691 
Mannich,  C.,  646 

Mannich,  C.,  and  Geilmann,  W.,  656 
Mannich,  C.,  and  Thiele,  966 
Mansfield,  Johannes,  with  Scholl,  685 
Markaryan,    Miss    V.,    with    Zal'kind, 

548,  566 

Markel,  K.  E.,  with  Crossfield,  941 
Marme*,  Wilh.,  with  Husemann,  330 
Martine,  C.,  with  Haller,  416,  421,  436, 

476,  478 

Mason,  F.  A.,  with  King,  782 
Mason,  John  E.,  and  Wilson,  John,  262 
Masson,  A.,  691 

Matignon,  C.,  and  Trannoy,  75,  259 
Matow,  N.,  with  Ipatief,  591,  722 
Matthews,  F.  E.,  and  Strange,  E.  H., 

213 

Maxted,  Edward  B.,  10,  1800,  954 
Mayer,  E.  W.,  with  Willstatter,  565,  569 
Mayer,  Max,  and  Altmayer,  411 
Mechel,   Lukas  von,   with   E.  Fischer, 

793 

Meigen,  W.,  and  Bartels,  G.,  598 
Meissel,  M.,  899 
Meissl,  E.,  325 
Meister,  Lucius,  and  Bnining,   Farbw, 

261,  299 
Meister,    Lucius,    and    Bruning,    with 

Imray,  228 
Melsens,  48 

Menozzi,  A.,  with  Koerner,  312 
Menschutkin,  N.,  38,  768,  769 
Mereshovski,  B.  K.,  192,  193,  472 
Merz,  V.,  with  Grucarevic,  899 
Metzger,  R.,  with  Schmidt,  454,  484 
Meyer,  Ernst  von,  231,  232 
Meyer,  Lothar,  294 
Meyer,  Richard,  and  Tanzen,  August, 

683 

Meyer,  Victor,  with  Cathcart,  893 
Meyer,  Victor,  and  Dulk,  L.,  224 


AUTHOR  INDEX 


359 


Meyer,  W.  A.,  with  Skita,  69,  545,  551, 

552,  554,  557,  559,  560 
Michael,  Arthur,  104,  239 
Michael,  Arthur,  and  Kopp,  Adolph, 

219 
Michael,  A.,  Scharf,  E.,  and  Voigt,  K., 

200 

Michiels,  Louis,  874 
Mignonac,  Georges,  380,  512,  809 
Millar,  W.  S.,  12 
Miller,  W.  Lash,  1800 
Milligan,  C.  H.,  538n,  706n,  772n,  778n 
Millon,  E.,  with  Reiset,  637 
Moeser,  Ludwig,  with  Naumann,  260, 

269 

Moissan,  Henri,  73,  136,  147 
Moissan,  H.,  and  Moureu,  Ch.,  637,  914 
Mom,  C.  P.,  with  Boeseken,  117,  546 
Mond,  Ludwig,  Langer,  C.,  and  Quincke, 

F.,  614 
Mond,  Ludwig,  Ramsay,  William,  and 

Shields,  John,  136,  137 
Moore,  H.  K.,  Richter,  G.  A.,  and  Van 

Arsdel,  W.  B.,  947,  952 
Moore,  R.  T.,  with  Egloff,  909 
Morrell,  R.  S.,  with  Fischer,  187 
Mouneyrat,  A.,  199,  284,  289 
Mouneyrat,  A.,  and  Pouret,  Ch.,  284 
Moureu,  Ch.,  with  Moissan,  637 
Mulder,  E.,  246 

Miiller,  A.,  and  Dubois,  H.,  285 
Miiller,  Hugo,  278,  795 
Muller,  N.  L.,  with  Kohn,  293 
Miiller,  287 
Miintz,  A.,  325 
Murat,  Marcel,  475 
Murat,  Marcel,  with  Mailhe,  384,  385, 

494 
Murat,  Marcel,  with  Sabatier,  343,  348, 

362,  364,  369,  389,  415,  449,  452,  453, 

455,  471,  475,  488,  523,  538,  714,  720, 

721 

Murat,  M.,  and  Amouroux,  G.,  414,  415 
Mylo,  B.,  with  Wohl,  725 

Nametkin,  S.  S.,  and  Abakumovskaya, 

L.  N.,  478 
Naumann,  Alex.,   Moser,  Ludwig,  and 

Lindenbaum,  Ernst,  260,  269 
Neuberg,  Carl,  268 
Neuberg,  C.,  with  Wohl,  237 


Nencki,  M.,  899 

Neogi,  P.,  and  Chowdhuri,  T.,  C.,  382 
Neumann,  A.,  with  Gabriel,  107 
Neumann,  G.,  137 
Niederhausern,  Heinrich  V.,  787 
Niggemann,  H.,  with  Fischer,  F.,  930 
Nikitine,  N.,  with  Krestinsky,  713 
Nord,  F.,  with  Skita,  555 
Norman,  W.,  542,  598,  940,  941,  945 
Norman,  W.,  and  Pungs,  W.,  598 
Norman,  W.,  and  Schlick,  F.,  80,  583 
Norton,  L.  M.,  and  Prescott,  C.  O.,  691 

(Economides,  S.,  795 
Oehme,  H.,  with  Paal,  555 
Oelsner,  K.,  with  Semmler,  570 
Oldenberg,  Babette,  with  Oldenberg,  272 
Oldenberg,    Hermann,    and   Oldenberg, 

Babette,  572 
Olivier,  S.  C.  J.,  893 
Orloff,  E.  L,  253,  254,  256 
Orndorf,  W.  R.,  223 
Ostromuislenskii,  I.  L,    and   Kelbasin- 

ski,  S.  S.,  784 
Ostromuislenskii,    I.  I.,  'and   Kosheler, 

I.  L,  214 

Ostwald,  W.,  8,  37,  140,  178,  180,  336 
Overton,  B.,  893 

Paal,  C.,  69,  72,  248,  251,  542,  544,  547, 

555 

Paal,  C.,  with  Skita,  555 
Paal,  C.,  and  Amberger,  C.,  69,  70,  545 
Paal,  C.,  Biehler,  F.,  and  Steyer,  H.,  70 
Paal,  C.,  and  Gerurn,  J.,  72,  546,  556 
Paal,  C.,  and  Hartmann,  Wilhelm,  180o, 

546 

Paal,  C.,  and  Hohenegger,  C,,  212,  548 
Paal,  C.,  and  Oehme,  H.,  555 
Paal,  and  Schwarz,  A.,  548,  558 
Paar,  W.,  with  Wolff enstein,  269n 
Padoa,  Maurizio,  485 
Padoa,  M.,  with  Carrasco,  497,  684 
Padoa,  M.,  and  Carughi,  A.,  489 
Padoa,  M.,  and  Chiaves,  C.,  490 
Padoa,  M.,  and  Fabris,  U.,  484,  491, 

642,  643 

Padoa,  M.,  and  Ponti,  371,  434,  487,  619 
Padoa,  M.,  and  Scagliarini,  G.,  647 
Parcus,  E.,  and  Tollens,  B.,  188 
Pardee,  A.  M.,  and  Reid,  E.  E.,  340n 


360 


AUTHOR  INDEX 


Parker,  H.  K.,  285n 

Passmore,  F.,  with  Fischer,  221 

Paterno,  E.,  282 

Patrick,  W.  A.,  75n,  180c 

Patry,  E.,  with  Pictet,  270 

Pauwels,  Joseph,  236 

Peachey,  S.  J.,  11,  104,  108 

Peligot,  E.,  with  Dumas,  691 

Perkin,  W.  H.,  107 

Perkin,  W.  H.  Jr.,  224,  795 

Perrin,  Jean,  180j 

Peter,  Arnold  H.,  691 

Pe"tricou,  288 

Petri,  Camille,  182 

P6trie,  75 

Pfau,  A.,  with  Houben,  569 

Phillips,  P.,  4 

Pictet,  Anne",  and  Lerczynska,  936 

Pictet,  Aime",  and  Patry,  E.,  270 

Piloty,  O.,  with  Fischer,  187 

Pinkney,  261n 

Piria,  R.,  328,  329,  851 

Pishchikov,  P.  V.,  with  Zal'kind,  38 

Plattner,  75 

Plotnikov,  V.  A.,  284 

Plummerer,  Rudolf,  with  Wilstatter,  835 

Ponder,  A.  C.,  with  Claisen,  798 

Ponti,  with  Padoa,  371,  434,  487,  619 

Pope,  Wm.  J.,  with  Atkinson.  282n 

Potter,  H.  M.,  with  Rosanoff,  324 

Prescott,  C.  O.,  with  Norton,  691 

Priebs,  Bernhard,  89,  803 

Pring,  John  N.,  525 

Prins,  H.  J.,  198,  216,  242,  625,  903 

Pungs,  W.,  with  Norman,  598 

Purgotti,  A.,  and  Zanichelli,  L.,  563 

Quincke,  F.,  with  Mond,  614 

Rabinovitz,  Louis,  with  Ellis,  601 
Rack,  E.,  with  Erdmann,  944 
Radziewanowski,  Cornelius,  886,  888 
Rai,  Hashmat,  265 
Rakitin,  W.,  with  Ipatief,  592 
Ramsay,  Wm.,  with  Mond,  136,  137 
Rather,  J.  B.,  and  Reid,  E.  E.,  601 
Raupenstrauch,  G.  A.,  795 
Ray,  J.  N.,  and  Dey,  M.  L.,  815n 
Raynaud,  A.,  with  Ducelliez,  292 
Reboul,  E.,  212 
Reformatski,  A.,  298 


Regnault,  V.,  131 

Reich,  75 

Reicher,  L.  T.,  178 

Reicher,  L.  T.,  with  Jarissen,  100 

Reid,  E.  Emmet,  lOn,  241n,  285n,  340n, 

538n,  696n,  772n,  816w,  778n,  947n 
Reid,  E.  Emmet,  with  Freas,  758n 
Reid,  E.  Emmet,  with  Helfrich,  278 
Reid,  E.  Emmet,  with  Kramer,  707n, 

708n,  744n 

Reid,  E.  Emmet,  with  Pardee,  340n 
Reid,  E.  Emmet,  with  Rather,  601 
Reid,  E.  Emmet,  with  Van  Epps,  812 
Reimer,  Marie,  and  Downes,  Helen  R., 

340n 

Reiset,  J.,  and  Millon,  E.,  637 
Remsen,  Ira,  and  Reiser,  E.  H.,  150 
Riban/J.,  216,  795 
Richardson,  A.  S.,  269n 
Riche",  397 

Richter,  G.  A.,  with  Moore,  947,  952 
Richter,  W.,  with  Semmler,  570 
Rideal,  E.  K.,  ISQj 

Rideal,  E.  K.,  and  Taylor,  H.  S.,  180s 
Rigaud,  L.,  328 
Rigaut,  A.,  with  Lescoeur,  230 
Rilliet,  A.,  and  Ador,  E.,  291 
Risse,  F.,  with  Semmler,  570 
Ritter,  H.,  with  Skita,  549,  642 
Rochleder,  F.,  340 
Roenisch,  P.,  with  Semmler,  570 
Rontgen,  W.  C.,  324 
Rosanoff,  M.  A.,  and  Potter,   H.   M., 

324 

Rosenmund,  K.  W.,  575 
Rosenmund,  K.  W.,  and  Zetsche,  F.,  545 
Rossel,  Arnold,  220 
Rost,  H.,  with  Darzens,  390,  459,  476 
Rothmund,  Victor,  324 
Roux,  Le"on,  199,  293 
Rosanov,  N.  A.,  193,  472 
Russanow,  A.,  280 
Rutala,  O.,  with  Ipatief,  211,  714 
Ryumshin,  P.  F.,  with  Chichibabin,  901 

Sabatier,  P.,  10,  146,  180,  364,  397,  399, 

400,  402,  416,  418,  511,  515,  590,  932, 

939 
Sabatier,  P.,  and  Espil,  Le*o,  12,  16,  56, 

80,  113,  114,  125,  338,  346,  358,  492, 

598 


AUTHOR  INDEX 


361 


Sabatier,  P.,  and  Gaudion,  G.,  631,  634, 
641,  643,  644,  645,  680,  681,  726 

Sabatier,  P.,  and  de  Godon,  F.,  801 

Sabatier,  P.,  and  Mailhe,  Alphonse,  75, 
77,  78,  112,  127,  162,  169,  170,  258, 
337,  343,  347,  363,  385,  387,  391,  404, 
406,  407,  420,  422,  430,  431,  437,  438, 
442,  457,  458,  461,  470,  475,  486,  495, 
521,  617,  621,  628,  641,  651,  655,  660, 
672,  673,  874,  677,  689,  693,  702,  704, 
706,  708,  709,  714,  715,  717,  731,  733, 
734,  735,  737,  739,  743,  744,  745,  746, 
762,  766,  769,  771,  772,  774,  777,  785, 
786,  787,  788,  789,  791,  794,  822,  823, 
824,  834,  839,  842,  843,  844,  845,  849, 
850,  852,  853,  856,  857,  858,  866,  873, 
876,  878,  916 

Sabatier,  P.,  Mailhe,  Alph.,  and  Gaudion, 
G.,  923 

Sabatier,  P.,  and  Murat,  M.,  343,  348, 
362,  364,  369,  389,  415,  449,  452,  453, 
455,  471,  475,  488,  523,  538,  714,  720, 
721 

Sabatier,  P.,  and  Senderens,  J.  B.,  26, 
111,  208,  343,  351,  362,  368,  370,  374, 
375,  376,  377,  b78,  379,  388,  394,  396, 
410,  413,  414,  419,  424,  425,  427,  433, 
435,  436,  446,  449,  451,  456,  460,  464, 
466,  467,  468,  469,  471,  475,  477,  481, 
482,  494,  497,  500,  501,  502,  503,  504, 
506,  508,  509,  510,  511,  512,  515,  517, 
518,  519,  520,  521,  526,  527,  530,  531, 
533,  534,  542,  614,  616,  619,  622,  637, 
652,  654,  656,  658,  659,  660,  664,  666, 
668,  683,  701,  832,  912,  914,  916,  919, 
920,  925,  928,  939 

Sainte-Claire-Deville,  H.,  216 

Sainte-Claire-Deville,  H.,  and  Debray, 
H.,  64,  822 

Sandmeyer,  T.,  91,  607,  608,  609 

Sastry,  S.  G.,  265 

Sayre,  R.,  with  Schorger,  235 

Saytzeff,  Michael,  536,  306 

Saytzeff,  Michael,  with  Kolbe,  165,  536 

Scagliarini,  G.,  with  Padoa,  647 

Schaeffer,  with  Kotz,  550 

Scharf,  E.,  with  Michael,  200 

Scheiber,  Johannes,  893 

Scheufelen,  Adolf,  293 

Schiaparelli,  Cesare,  293 

Schibsted,  Helge,  with  Hofmann,  824 


Schicht,  G.,  Akt.-Ges.,  942 
Schicht,  G.,  Akt.-Ges.,  and  Grim,  A.,  846 
Schiel,  J.,  282 

Schimmel,  A.,  with  Boeseken,  224 
Schlick,  F.,  with  Norman,  80 
Schlinck,  H.,  and  Co.,  960 
Schmaedel,  W,  von,  with  Dimroth,  816 
Schmidt,  C.,  with  Schraube,  206 
Schmidt,  J.,  and  Fischer,  Ernst,  571 
Schmidt,  J.,  and  Metzger,  R.,  454,  484 
Schneider,  W.  von,  210 
Schnellenberg,  Albert,  with  Sonn,   565 
Schoenbein,  C.  F.,  180o 
Scholl,    Roland,    and    Mansfield,  Jo- 
hannes,   685 

Scholl,  Roland,  and  Seer,  Christian,  685 
Scholl,  R.  Seer,  Chr.,  and  Wellzenbock, 

R.,  685 

Scholtz,  M.,  799 
Schone,  Em.,  160 
Schonfeld,  H.,  944 
Schorger,  A.  W.,  930 
Schorger,  A.  W.,  and  Sayre,  R.,  235 
Schraube,  C.,  and  Schmidt,  C.,  206 
Schrohe,  A.,  212 
Schrotter,  H.,  with  Kekute,  199 
Schulke,  Kurt,  with  Heller,  889n,  898 
Schulman,  G.  G.,  with  Ipatief,  838 
Schultze,  Paul,  320 
Schumpelt,  K.,  with  Hofmann,  271 
Schtitzenberger,  637 
Schwartz,  A.,  with  Kelber,  69,  548 
Schwarz,  A.,  with  Paal,  548,  558 
Schwoerer,  941,  959 
Sdzitowecky,  W.,  with  Ipatief,  713 
Seelig,  E.,  283,  285,  286 
Seer,  Christian,  with  Scholl,  685 
Seiichideno,  115 

Seligman,  R.,  and  Williams,  P.,  12 
Semmler,  F.,  W.,  and  Becker,  C.,  570 
Semmler,  F.,  W.,  Jonas,   K.   G.,  and 

Oelsner,  K.,  570 
Semmler,   F.   W.,   Jonas,   K.   G.,   and 

Richter,  W.,  570 
Semmler,   F.   W.,   Jonas,   K.   G.,   and 

Roenisch,  P.,  570 

Semmler,  F.  W.,  and  Risse,  F.,  570 
Senden,  G.  H.  von  with  Boeseken,  664 
Senderens,  J.  B.,  78,  511,  694,  696,  700, 

713,  718,  719,  725,  840,  844,  849,  855, 

858,  873,  874,  878,  881 


362 


AUTHOR  INDEX 


Senderens,  J.  B.,  with  Sabatier,  26,  111, 
208,  343,  351,  362,  368,  370,  374,  375, 
376,  377,  378,  379,  388,  394,  396,  410, 
413,  414,  419,  424,  425,  427,  433,  435, 
436,  446,  449,  451,  456,  460,  464,  466, 
467,  468,  469,  471,  475,  477,  481,  482, 
494,  497,  500,  501,  502,  503,  504,  506, 
508,  509,  510,  511,  512,  515,  517,  518, 
519,  520,  521,  526,  527,  530,  531,  533, 
534,  542,  570,  614,  616,  619,  622,  637, 
652,  654,  656,  658,  659,  660,  664,  666, 
668,  683,  701,  832,  912,  914,  916,  919, 
920,  925,  928,  939 

Senderens,  J.  B.,  and  Aboulenc,  Jean, 
598,  758,  759,  760 

Se'ne'chal,  A.,  with  Colin,  11 

Seyewetz,  A.,  and  Gibello,  221 

Shaw,  T.  W.  A.,  601 

Shroeter,  G.,  481n 

Shukow,  A.  A.,  942 

Siemens,  397 

Silber,  P.,  with  Ciamician,  150 

Silbermann,  J.  T.,  with  Favre,  131 

Silva,  R.  D.,  890 

Siveke,  with  Leprince,  542 

Skita,  A.,  71,  420,  546,  548,  553,  559, 
560 

Skita,  A.,  and  Brunner,  W.,  561 

Skita,  A.,  and  Meyer,  W.  A.,  69,  545, 
551,  552,  557,  559,  560 

Skita,  A.,  Meyer,  W.  A.,  and  Bergen, 
J.  von,  554 

Skita,  A.,  and  Nord,  F.,  555 

Skita,  A.,  and  Paal,  C.,  555 

Skita,  A.,  and  Ritter,  H.,  549,  642 

Skraup,  H.,  182 

Smirnof,  V.  A.,  369,  465 

Snethlage,  H.  C.  S.,  12 

Soc.  de  Ste*arinerie,  and  Savonnerie  de 
Lyon,  949 

Sommelet,  Marcel,  818,  889,  899 

Sommer,  Rudolf,  268 

Sonn,  Adolf,  and  Schnellenberg,  Albert, 
565 

Sonnenfeld,  Eugen,  with  Willstatter,  251 

Spier,  Arthur,  with  Fischer,  753 

Spilker,  A.,  with  Kramer,  217 

Spohr,  J.,  324 

Sponagel,  Paul,  with  Ullmann,  904 

Sprent,  C.,  413,  713 

Squibb,  Edward  R.,  161,  180a,  837 


Staudinger,  H.,  and  Klever,  H.  W.,  235 

Steinkopf,  Wilhelm,  and  Freund,  Mich- 
ael, 931 

Steyer,  H.,  with  Paal,  70 

St.  Gilles,  Pean  de,  with  Berthelot,  758n 

Stock,  A.,  and  Guttmann,  O.,  8 

Stockhausen,  F.,  and  Gattermann,  L., 
886 

Stolid,  R.,  201 

Stone,  W.  E.,  and  Tollens,  B.,  727 

Strange,  E.  H.,  with  Matthews,  213 

Strecker,  Adolph,  240 

Strieker,  Otto,  with  Kekule",  182 

Strutt,  R.  J.,  180c 

Sulzberg,  N.;  with  Thiele,  203 

Sutherland,  M.  J.,  with  Henderson,  463 

Suto,  K.,  268 

Sutton,  Lena  M.,  with  Evans,  691 

Taboury,  Fe"lix,  with  Bodroux,  421 
Taboury,  F61ix,  with  Godchot,  390,  421, 

436, 856 

Tafel,  J.,  with  Fischer,  237 
Tanatar,  S.,  182,  193 
Tanret,  C.,  188 

Tanzen,  August,  with  Meyer,  683 
Taylor,  Clara  M.,  with  Easterfield,  843 
Taylor,  H.  S.,  1806,  1800,  180? 
Taylor,  H.  S.,  with  Rideal,  180s 
Tchougaeff,  L.,  and  Fomin,  W.,  570 
Teuchert,  R.,  312 
Tltfnard,  with  Dulong,  637 
Thiele,  with  Mannich,  966 
Thiele,  Johannes,  and  Sulzberger,  N., 

203 

Tiemann,  Ferd.,  191 
Tiemann,  Ferd.,  and  Haarmann,  Wilh., 

329 

Tiemann,  F.,  and  Kriiger,  Paul,  198,  800 
Tikhvinskii,  V.  M.,  with  Arbusow,  611, 

633,  635 

Tilden,  W.  A.,  with  Armstrong,  198 
Tingle,  J.  B.,  and  Blanck,  F.  C.,  269n 
Tischenko,  V.  E.,  228,  299 
Tollens,  B.,  with  Parcus,  188 
Tollens,  B.,  with  Stone,  727 
Tollens,  B.,  with  Yoder,  727 
Tollens,  B.,  and  Wigand,  P.,  83 
Tornthwaite,  75 

Trannoy,  with  Matignon,  75,  259 
Traube,  M.,  73 


AUTHOR  INDEX 


363 


Trey,  H.,  317 

Tribe,  Alfred,  with  Gladstone,  165,  166, 

169.  785 

Trillat,  A.,  73,  249,  253,  256 
Trillat,  A.,  and  Gambier,  781 
Trunov,  B.  V.,  with  Chelintzev,  805 
Tschelinzeff,  W.,  301 
Turbaba,  D.,  22 
Turner,  Edward,  10,  116 
Twomey,  T.  J.,  with  Egloff,  908 
Tyndall,  180j 

Uklonskaja,  Miss,  N.,  with  ZeUnski,  649 

Ullmann,  Fritz,  901 

Ullmann,  F.,  and  Sponagel,  Paul,  904 

Valpy,  O.  H.,  and  Lucas,  O.  D.,  933 
Van  Arsdel,  W.  B.,  with  Moore,  947,  952 
Van  der  Scheer,  J.,  with  Boeseken,  879 
Van  der  Weide,  O.  B.,  with  Boeseken, 

117,  546 
Van  Ekenstein,  W.  A.,  with  Lobry  de 

Bruyn,  186 
Van  Ekenstein,  W.  A.,  and  Blanksma, 

J.  J.,  186 
Van  Epps,  G.  D.,  and  Reid,  E.  Emmett, 

812 

Van't  Hoff,  139,  175 
Varet,  Raoul,  and  Vienne,  G.,  241 
Vavon,  G.,  63,  567,  568,  570 
Vavon,  with  Lespieau,  566 
Vavon  and  Faillebin,  565 
Veley,  V.  H.,  8,  269n 
Veraguth,  H.,  with  Willstatter,  480 
Verein,   Chininfabr.  Zimmer,  and  Co., 

572,  604 

Verein,  f.  Chem.  Ind.,  254 
Verinigte  Ch.  Werke,  946 
Vienne,  G.,  with  Varet,  241 
Vignon,  Le*o,  269n,  540 
Villiers,  A.,  153 

Vogt,  J.  D.  de,  with  Boeseken,  879 
Voigt,  with  Michael,  200 
Vorlander,  D.,  and  Hobohm,  K.,  799 

Wacker,  L.,  274 

Waldschmidt-Leitz,  Ernst,  with  Will- 
statter, 62n,  167n,  562n,  563n,  573n, 
943n,  947n. 

Wallach,   O.,   198,  205,   546,  552,   797 

Wallach,  O.,  and  Wiisten,  M.,  97 


Ward,  A.  L.,  with  Boehner,  811 
Waser,  E.,  with  Willstatter,  480,  535, 

571 
Weismann,  Charles,  and  Garrand,  S.  F., 

654n 

Weiss,  J.  M.,  and  Downs,  C.  R.,  260n 
Wells,  A.  A.,  with  Ellis,  949 
Wellzenbock,  R.,  with  Scholl,  685 
Wesson,  David,  967n 
Wilbaut,  J.  P.,  683 
Wieland,  Heinrich,  251 
Wieland,  H.,  and  Wishart,  R.  S.,  579 
Wigand,  P.,  with  Tollens,  83 
Wiggers,  A.,  307 

Wilbuschewitch,  M.,  941,  945,  961 
Wild,  W.,  with  Engler,  150 
Wilde,  M.  P.  von,  342,  526 
Wilfarth,  H.,  272 
Willgerodt,  C.,  283 

Willgerodt,  C.,  and  Genieser,  Ad.,  238 
Williams,  C.  E.,  with  Bedford,  939,  941, 

943 

Williams,  P.,  with  Seligman,  12 
Williams,  R.  R.,  and  Gibbs,  H.  D.,  254n 
Williamson,  Alexander,  159,   169,  848, 

851 

Willstatter,  Richard,  542,  562,  563 
Willstatter,  Richard,  and  Bruce,  James, 

293,  473 

Willstatter,  R.,  and  Hatt,  D.,  569,  571 
Willstatter,  R.,  and  Heidelberger,  M., 

571 
Willstatter,  R.,  and  Jacquet,  D.,  563, 

569,  571 
Willstatter,  R.,  and  Kametaka,  T.,  197, 

472,  479 

Willstatter,  R.,  and  King,  V.,  569,  571 
Willstatter,  R.,  and  Mayer,  E.  W.,  565, 

569 
Willstatter,  R.,  and  Pummerer,  Rudolf, 

835 
Willstatter,  R.,  and  Sonnenfeld,  Eugen, 

251 

Willstatter,  R.,  and  Veraguth,  H.,  480 
Willstatter,  R.,  and  Waser,  E.,  480,  535, 

571 

Willstatter,  Richard,  and  Waldschmidt- 
Leitz,  Ernst,  62n,  167n,  562w,  563n, 

573n,  943n,  947n 
Wilsmore,  N.  T.  M.,  829 
Wilson,  John,  with  Mason,  262 


364 


AUTHOR  INDEX 


Wimmer,  K.  H.,  and  Higgins,  E.  B.,  944 

Winkler,  Clemens,  73 

Wipperinann,  R.,  230 

Wischnegradsky,  A.,  210 

Wishart,  R.  S.,  with  Wieland,  579 

Witzemann,  Edgar,  J.,  725 

Wohl,  A.,  324 

Wohl,  A.,  and  Mylo,  B.,  725 

Wohler,  F.,  and  Liebig,  Justus,  220 

Wohler,  F.,  and  Mahia,  75 

Wohler,  Lothar,  with  Engler,  137,  154 

Wohl,  A.,  94 

Wohl,  A.,  and  Neuberg,  C.,  237 

Woker,  Miss  Gertrude,  180; 

Wolffenstein,  R.,  and  Boters,  O.,  269 

Wolffenstein,   Richard,   and   Hartwich, 

Frank,  893 

Wolffenstein,  R.,  and  Paar,  W.,  269n 
Wollemann,  J.,  with  Borsche,  546 
Wollrath,  A.,  278 
Woltman,  A.,  964 
Woog,  Paul,  257,  259 
Wozelka,  Hermann,  with  Frank,  223 
Wurtz,  Adolphe,  11,  219,  307,  334,  605 
Wusten,  M.,  with  Wallach,  97 

Yoder,  P.  A.,  and  Tollens,  B.,  727 
Youssouffian,  with  Haller,  341 


Zagumenni,  A.,  692 

Zal'kind,  Y.  S.,  548,  566 

ZaPkind,    Y.    S.,    and    Kvapishevskii. 

K.  V.,  548,  566 
Zal'kind,  Y.  S.,  and  Miss  Markaryan, 

V.,  548,  566 
Zal'kind,  Y.  S.,  and  Pishchokov,  P.  V., 

38 

Zanetti,  C.  U.,  742 
Zanetti,  J.  E.,  and  Egloff,  G.,  907 
Zanichelli,  L.,  with  Purgotti,  563 
Zdrawkowitch,  Milan  R.,  62 
Zeise,  62 
Zelinski,  H.,  302 
Zelinsky,  N.  D.,  390,  472,  478,  534,  535, 

649,  906,  934 
Zelinsky,  N.  D.,  and  Glinka,  N.,  648, 

822 
Zelinsky,  N.  D.,  and  Herzenstein,  Miss 

Anna,  649 
Zelinsky,  N.,  and  Uklonskaja,  Miss  N., 

649 

Zetsche,  F.,  with  Rosenmund,  545 
Zincke,  Th.,  with  Breuer,  220 
Zincke,  Th.,  with  Kekule*,  222 
Zinin,  N.,  203,  220 
Zsigmondy,  R.,  18Q; 


SUBJECT  INDEX 


(References  are  to  Paragraphs:   a  number  followed  by  "n"  designates  a  note.) 


Absorption  of  gases,  131,  135 
Acenaphthene,  hydrogenated,  482 
Acetaldehyde,  219,  222,  261,  700,  724, 
725 

into  acetals,  780,  782 

from  acetylene,  92,  309,  310 

as  catalyst,  105,  310,  312 

condensed,   52,   592,   780,   782,   795, 
796,  801,  807 

crotonized,  795,  801 

decomposed  by  Pd.,  623,  680 

into  ester,  228 

formed,  1800,  200 

hydrogenated,    432,    439,    494,    538, 
593,  664,  668,  670,  673 

with  hydrogen  sulphide,  810 

by  oxidation,  249,  254,  256,  268 

oxidised,  255,  260,  261 

preparation  of,  309 
Acetal,  by  oxidation,  249 
Acetals,  81,  97,  175,  249,  305,  779-783 

formed,  81,  106,  249 

hydrolysis  of,  322,  323 

preparation  of,  782 
Acetamide,  dehydrogenated,  811 

hydrolyzed,  336,  386 
Acetanhydride,  107 

decomposed,  829 

in  esterification,  761 

into  ketone,  857 
Acetanilide  in  synthesis,  901 
Acetic   acid,   into   acetone,    161,    180a, 
840-845 

from  acetylene,  255 

from    alcohol,    48,    150,     255,     257, 
261 

as  catalyst,  106,  215,  687,  780 

chlorinated,  280 

decomposed,  831,  843 

esterified,  750,  758,  760,  771 

esters  of  decomposed,  863 


formed,  1806 

into  nitrile,  812 

by  oxidation,  48,  150,  255,  257,  261 

retarder,  11 
Acetols,  783 
Acetone,  into  acetol,  783 

with  chloroform,  238 

condensed,  238,  783,  797,  797n,  798, 
800,  801,  805 

condensed  with  aldehydes,  798 

condensed  with  benzaldehyde,  798 

condensed  with  citral,  800 

condensed  with  o.nitrobenzaldehyde, 
798 

crotonized,  797,  798 

decomposed.  620,  659,  665,  668 

formed,  161,  180a,  249,  309,  831,  837, 
844 

hydrogenated,  435,  Co  503,  Cu  594, 
Fe  593,  Ni  588,  598,  Pt  567,  Zn  595 

by  oxidation,  249,  254a 

preparation  of,  161 
Acetone-oxime  hydrogenated,  383 
Acetonitrile  as  catalyst,  108,  605 

formed,  871 

polymerized,  50,  231,  427 
Acetonyl-acetone  hydrogenated,  440 
Acetophenone,  848,  849 

catalytic  solvent,  38 

condensed,  799 

by  Friedel  and  Crafts  reaction,  891, 
893 

hydrogenated,    389,    455,    538,    539, 

568 

Acetophenone-oxime  hydrogenated,  384 
Acet-oxime  hydrogenated,  383 
Acetyl-acetone  hydrogenated,  439,  595 
Acetyl-brom-glucose  condensed,  793 
Acetyl  chloride  formed,  280 

in  F.  and  C.  reaction,  891-893 
Acetylation,  81,  240 


365 


366 


SUBJECT  INDEX 


Acetyl-chloramino-benzene  isom.,  202 
Acetyl-cyclo-hexene  hydrogenated,  476 
Acetyl-diphenyl-amine,  syn.,  901 
Acetylene,  38,  102,  308-310 

condensed,  686,  Co  928,  Cu  916,  Fe 
928,  Ni  925-928 

condensed  with  benzene,  241 

decomposed,  637,  913-920 

formed,  409 

hydrated,  27,  92,  308 

hydrogenated  by  Co,  501,  Cu  518,  Fe 
506,  Ni  423,  424,  Pd  548,  558,  Pt 
342,527 

polymerized,  212,  914 
Acetylene  bond,  migration  of,  192 
Acetylene     compounds     hydrogenated, 
423-425,  518,  527,  548,  558,  566, 
577,  601 
Acetylene    glycols  hydrogenated,    548, 

566,  577 

Acetylene    hydrocarbons    decomposed, 
913-919 

hydrated,  308 

polym.,  212 

Acetylene  tetrabromide,  289,  897 
Acetylene  tetrachloride,  199 
Acetyl-vanilline  hydrogenated,  568 
Acid  amides  hydrolyzed,  331 
Acid  anhydrides  formed,  872 

hydrogenated,  392 

into  ketones,  857 
Acid  chlorides,  243 

with  ammonia,  813 

decomposed  by  AlCls,  625 

in  F.  and  C.  reaction,  891-894 

hydrogenated,  575 
Acids,  in  formation  of  acetals,  783 

from  alcohols,  150,  246,  275 

catalysts,  17,  81 

decomposed,  171,  820-856 

in  depolymerization,  234 

in  esterification,  748-756 

hydrogenated,  422 

in  hydrolysis,  175,  305 

in  hydrolysis  of  glucosides,  175 

in  inversion  of  sugar,  175 

in  isomerization  181-182 
Aconitic  acid  hydrogenated,  558 
Acridine  hydrogenated,  491 

oxidised,  270 
Acridone,  270 


Acroleme,  101,  249,  658,  680,  713,  725, 
726 

hydrogenated,  419 
Acrylic  acid  hydrogenated,  417 

by  oxidation,  249 

Activated  charcoal  as  catalyst,  282n 
Active  alkaloids  as  catalysts,  836 
Active  modifications,  180i 
Adipic  acid,  251 
Adsorption  theory,  180c 
Aeration  of  Pt.  black,  563 
Agitation  in  catalysis,  541 

in  hydrogenation,  957 
Albumin,  stabilizer  for,  Pd,  69 
Alcohol  eliminated,  817 

as  source  of  H,  537 

as  solvent  in  hydrogenation,  599 

toxic  to  Pt.  black,  117 
Alcoholates,  299 
Alcohols  with  aldehydes,  784 

decomposed,  1800,  538,  CdO  674, 
C  679,  SnO  673,  Zn  678 

dehydrated,  28,  75,  98,  99,  138,  180ft 

dehydrogenated,  28,  650-679 

by  hydration  of  hydrocar.,  305 

hydrogenated,  416 

oxidised,  246,  249,  254,  268 
Alcohols,  aromatic,  hydrogenated,  369, 

465 

Alcoholysis,  340,  340n 
Aldehydes,  236,  653,  655,  668,  701,  723 

acetylated,  240 

into  acetals,  780-783 

from  alcohols,  15,  48,  246,  650 

condensed,  90,  237,  239,  240,  794- 
810 

crotonized,  794-801 

decomposed,  618-623,  532,  549 

dehydrated,  794-802 

by  depolymerization,  234 

into  esters,  225-228 

formed,  15,  28,  31,  48,  75,  142,  200, 
208,  866 

hydrogenated,  388,  419,  432-434, 
568,  Co  503,  Cu  522,  Fe  506,  593, 
Ni  588,  602,  Pt  567 

by  oxidation,  15,  48,  258-261,  268, 
275 

from  oximes,  268,  332 

with  phenols,  792 

polymerized,  82,  106,  218-228 


SUBJECT  INDEX 


367 


preparation  of,  851-854 
Aldolization,  82,  83,  95,  97,  219,  221 
Aldols  depolymerized,  234 

formed,  219 
Aldoximes  dehydrated,  814 

hydrogenated,  383,  384,  514 

isomerized,  204 

Alicyclic  ketones  hydrogenated,  436 
Aliphatic   hydrocarbons    cracked,    911, 

912 

Alizarine,  274, 328 
Alkalies  in  hydrolysis,  305 
Alkaline    bisulphates    in   esterif.,    748, 
759,  760 

carbonates  as  cats.,  97 

halides  elim.,  904 
Alkaloids  as  cats.,  836 
Alkyl-anilines,  729 

Alkylation  of  arom.  hydrocar.,  884-890 
Alkyl  bromides  decomposed,  876 

in  F.  and  C.  syn.,  885 

in  Grignard  reaction,  302 

isomerized,  199,  200 

Alkyl  chlorides   decomposed,    86,  876- 
882 

in  syn.,  883-889 
Alkyl  halides,  104,  300-304,  883-885 

isomerized,  876 
Alkyl  iodides,  304 

decomposed,  876 

in  F.  and  C.  reaction,  885 
Alkyl  phenol  ethers,  494,  789 

hydrogenated,  464 
Alkyl  piperidines,  741 
Alkyl  sulphides,  626-628,  743,  744 
Alkyl  ureas,  431 
Allenic  hydrocarb.  hydrated,  308 

isomerized,  192 
Allyl  alcohol  601,  680,  740 

dehydrated,  713 

esterified,  757 

isomerized,  208,  658 

oxidised,  249 

hydrogenated,  416,  558 
Allyl  amine  as  cat.,  836 
Allyl  benzoate,  766 
Allylene  hydrated,  309 

polymerized,  212 
Allyl  iodide,  605 
Allyl  ketones  hydrogenated,  602 
Allyl  mercaptan,  744 


Almond  oil,  938 
Alumina  as  carrier,  127 
as  catalyst,  75,  78,   169,   ISQj,  540, 

586,  624,  676,  693,  694,  700,  714, 

721,  722,  732,  740,  784,  797n,  807- 

814,  825 

in  cracking,  906,  934 
decomp.  chlorides,  881 
decomp.  esters,  861n,  866,  872-874 
decomp.  hexane,  920 
dehydration     catalyst,     142,      180(7, 

180fc,   651,   686,    743,    784,    791 
esterification  cat.,  764 
isomerizes  unsat.  hydroc.,  190,  200 
ketone  cat.,  840,  849 
life  of,  708 
mercaptan  cat.,  746 
polymeriz.  unsat.  hydroc.,  211 
preparation  of,  77,  706,  713,  714 
Aluminum  cat.,  284,  886,  901 
in  cracking,  906 
dec.  hydrocarb.,  920 
influence  on,  Pd,  946 
Aluminum  alcoholates,  12,  299 
amalgam,  293 
catalyst,  51 

dissolved  in  alcohols,  12 
oxidation  cat.,  254 
Aluminum   bromide,  bromination  cat., 

93,  293 
catalyst,  298 
chlorination  cat.,  289 
isomeriz.  cat.,  119 
in  F.  and  C.  reaction,  893 
Aluminum    chloride,    bromination  cat., 

293 

with  carbon  monoxide,  298 
catalyst,  6,  33,  87,  173-174,  239-243, 

293-297,  687,  728,  795,  797,  803, 

806,    817-819,    877-879,    884-900, 

903,  929-931,  935 
chlorination  cat.,  283,  284 
condensation  cat.,  903 
cracking  cat.,  935 
on  cymene,  930 
dehydrogenation  cat.,  638,  685 
in  F.  and  C.  reaction,  896-900 
on  hydrocarb.,  929-931 
on  naphthalene,  931 
on  pinene,  931 
polymerizes  hydrocarb.,  211,  216 


368 


SUBJECT  INDEX 


regenerated,  935 

in  sulphonation,  295 

with  sulphur  dioxide,  297 

theory  of  action,  173,  687,  728 

on  thiophenol,  629 

on  xylene,  930 
Aluminum  ethylate  polymer,  aids.,  228 

preparation,  299 

Aluminum  phosphate,  99,  719,  726 
Aluminum  powder  cat.,  901 
Aluminum  salts  dehydration  cat.,  717 

in  nitration,  269n 
Aluminum  sulphate  cat.,  99,  696,  706, 

717, 725, 759,  760 

Aluminum   turnings   chlorination   cat., 
284 

in  F.  and  C.  reaction,  886 

with  mercuric  chloride,  886 
Amarine  formed,  194 
American  hardened  oils,  967n 
American  petroleum,  908,  928,  932 
Amides  dehydrated,  811 

hydrogenated,  386,  Cu  514,  Ni  386 

hydrolized,  305,  311,  331,  335,  336 

from  nitriles,  311 

from  oximes,  204,  205 

polymerized,  233 

syn.  by  F.  and  C.  reaction,  895 
Amines,  170,  426,  430,  431,  513,  514, 
600,  682 

cond.  cat.,  803 

decomp.  Ni,  631 

dehydrogenated,  681,  682 

formed,  15,  170,  382,  383,  731-742 

hydrogenated,  496 

by  hydrogenation,  382,  383 

oxidised,  268 

from  oximes,  383 

secondary,  682 

suphurized,  296 

syn.  of,  683,  731-742 

in  vulcaniz.  of  rubber,  104 
Amino-acetophenone,  545,  557 
Amino-benzoic  acid  hydrogenated,  569 
Amino-caproic  acid  into  lactam,  205 
Amino-cyelo-hexanes  dehydrogenated, 

642 

Amino-cyclo-hexane-carbonic  acid,  569 
Amino-«thyl  alcohol  oxid.,  268 
Amino-malonic  nitrile,  230 
Amino-naphthol,  564 


Amino-nitrobenzene,  syn.  of,  901 
Amino-phenol,  630,  632 
Amino-phenols,  381.  536 
Amino-succinic  acid,  312 
Ammonia  into  amines,  901 

condensed  with  aids.,  807-809,   812, 
813 

condensed  with  ketones,  809 

condensation  cat.,  803,  804 

in  cracking,  933 

decomposition  cat.,  637 

eliminated,  611,  631-633 

with  esters,  871 

by  hydrogenation,  377 

from  nitric  oxide,  368,  374 

oxidised,  249,  256 

polymeriz.  cat.,  104 

syn.  of,  180s,  180f,  180w,  342 
Ammonium  alum,  784 
Ammonium  chloride  cat.,  97,  783 
Ammonium  isosulphocyanate,  104,  207 
Ammonium  nitrate,  97,  256,  375,  376 

783 

Ammonium  nitrite,  375 
Ammonium  salts  in  esterif.,  748 
Ammonium  sulphate,  97,  783 
Amount  of  catalyst,  598,  951 
Amount  of  acids  in  esterif.,  753-756 
Amphoteric  hydroxides,  859 
Amygdalin,  329 
Amyl-amine,  486,  631,  681 
Amyl  alcohol,  150,  673 
Amyl-benzine  hydrog.,  569 
Amylene,  626,  696,  746;  871,  929 

dec.  by  A1C1.,,  929 

hydrated,  306 

hydrogenated,  558,  565 

preparation  of,  706n 
Amyl  nitrite,  tox.  to  cats.,  116 
Amyl  oleate  hydrogenated,  526 
Amyl  stearate,  526 
Anethol  hydrogenated,  Ni  590,  601 
Anhydrides  hydrogenated,  392 
Aniline,  469,  495,  497,  531,  536,  538, 
545,  554,  557,  576,  630-632,  683, 
790 

alkylated,  729,  740 

eliminated,  634,  635 

formed,  165,  277,  378,  380,  381 

hydrogenated,  466,  467,  569 

by  hydrogenation,  277,  378,  380,  381 


SUBJECT  INDEX 


369 


manufacture,  378,  511 

methylated,  729 

oleate  hydrogenated,  Ni  601 

oxidised,  256 

in  syn.,  901 

toxicity  to  cats.,  116 
Aniline  black,  260n,  271 
Aniline  hydrobromide  as  cat.,  726 
Anilines,  substituted,  468 
Animal  charcoal,  carrier,  946 

catalyst,  48,  282 
Anisalcohol,  568 
Anisaldehyde  condensed,  808 

hydrogenated,  568 

polymerized,  220 
Anisdidines,  632 
Anisolne,  220 
Anisol  condensed,  806 

hydrogenated,  464,  494,  589 

neg.  cat,,  11,  303 

preparation,  789 

Anthracene,  274,   806,   897,   908,   909, 
914,  921 

from  acetylene,  914 

condensed,  806 

by  cracking,  908,  909 

decomposed,  921 

by  F.  and  C.  reaction,  897 

hydrogenated,  29,  363,  483,  592 

oxidised,  257,  260n,  262,  262n,  269, 

271 

Anthracene  blue  by  oxide.,  274 
Anthracene  hydrides  dehyd.,  642,  728 
Anthraquinone,  257,  260n,   262,  262n, 
269,  271,  839,  846 

sulphonated,  816 

syn.  by  F.  and  C.,  893 
Anthraquinone  disulphonic  acids,  816 
Anthraquinone  sulphonic  acids,  816 
Antimony  cat.,  47 
Antimony  chloride  cat.,  90,  216 

chlorination  cat.,  283,  287 

in  F.  and  C.,  899 
Apparatus  for  dehydration,  717 

for  dehydrogenation,  654 

for  hydrogenation,   584,   585,   597, 

957-964 
Arabinose  dehydrated,  727 

from  HCHO,  221 

multirotation,  188 
Arabite  oxid.,  268 


Araboketose  by  oxid.,  268 
Arabonic  acid,  187 
Arachidic  esters,  937 
Arbutin  hydrolyzed,  328 
Argon  abs.  by  C,  180d 
Aromatic  acids  dec.,  830 

esterified,  758,  766 

hydrogenated,  471 
Aromatic  alcohols  condensed,  728 

hydrogenated,  369,  465 

reduced,  369 
Aromatic  aldehydes  hydrogenated,  388, 

568 
Aromatic  amides  syn.  by  F.  and  C., 

895 
Aromatic  amines  with  alcohols,  740 

hydrogenated,  466 

syn.,  901 

thioureas,  630 

Aromatic  bromides  from  diazo.,  608 
Aromatic  chlorides  from  diazo,  607 
Aromatic  ethers,  494 
Aromatic  hydrocarbons  from  CjH*,  926 

alkylated,  877-890 

brominated,  291-293 

by  cracking,  932 

decomp.,  921,  930 

hydrogenated,  446 

oxidised,  269 
Aromatic   ketones   hydrogenated,    389, 

455.  523,  590 

Aromatic    nitro-comps.     hydrogenated, 

511,600 
Aromatic  nucleus   hydrogenated,   444- 

456,  Cu  594,   Fe  593,  Ni  589,  Pd 
556,  578,  Pt  534,  560,  569 

Aromatic  rings  hydrogenated,  444-456, 

534 

Arsenic  toxic  to  Pt,  116 
Arsenic  acid,  691 
Arsenious  oxide  toxic  to  Pt,  116 

transformed,  73 
Arsine  cat.  poison,  1800 

decomp.  of,  8 

Asbestos  as  carrier,  126,  941 
Asparagine  formed,  312 
Aspartic  imide  hydrogenated,  312 
Asymmetric  dec.  of  acids,  836 
Atoms,  migration  of,  199 
Auto  catalysis,  8 
Autoclave  for,  H2,  597 


370 


SUBJECT  INDEX 


Auto  oxidation,  150,  151 
Azobenzene,  by  hydrogenation,  511 

hydrogenated,  497,  554 
Azo-compounds  hydrogenated,  600 
Azoxy-compounds  hydrogenated,  600 

Bakelite,  792 

Baku  petroleum,  444 

cracked,  934 

Barium  carbonate  cat.,  98,  838 
Barium  chloride  cat.,  86,  876,  880 
Barium  hydroxide  cond.  agt.,  800 
Barium  peroxide  poly,  cat.,  214 
Barium  salts  decomp.,  837 
Barium  soaps  neg.  cat.,  115 
Bases  as  cats.,  83 

in  hydrolysis,  175,  178 
Bauxite  cat.,  706,  706n 
Beef  tallow,  938 
Benzal-acetone,  798 
Benzal  chloride,  320,  890 
Benzaldehyde,  into  acetal,  783 

acetalated,  240 

from  benzal  chloride,  320 

condensed,   89,   798,   799,   803,   804, 
807,  808 

decomposed,  Ni  620,  Pd  623 

into  ester,  225 

formed,  165,  575;  657,  674 

by  F.  and  C.  react.,  297,  298 

by  hydrolysis,  329 

by  oxidation,  249,  257,  259,  260n,  268 

hydrogenated,   Fe  593,   Ni  388,   Pd 
549,  560,  Pt  568,  thoria  538 

polymerized,  220 
Benzaldoximes  transformed,  185 
Benzamide  by  F.  and  C.  syn.,  895 
Benzanthrone,  685 

Benzene,  518,  593,  620,  641,  643,  649, 
657,  674 

from  C2H2,  914-916 

brominated,  292 

chlorinated,  278,  284,  285 

condensed,  806,  817-819 

by  cracking,  908,  909 

in  cracking,  907 

from  cymene,  930 

decomposed,  907,  921 

in  F.  and  C.  syn.,  894,  897 

in  Grignard  syn.,  300 

hydrogenated,    26,    344,    361,    362, 


444-447,  534,  589,  947n,  Co  502, 
Pt  560,  569 

from  hydrogenation,  370,  378,  388 

neg.  cat.,  11 

oxidised,  260n,  263,  268,  276 

sulphonated,  815 

from  xylene,  930 
Benzene  homologs  from  acetylene,  518 

hydrogenated,  447-450,  Co  502,  Pt 

569 

Benzene  ring  hydrogenated,  Ni  603 
Benzene  sulphinic  acid,  297 
Benzhydrol,  538,  728,  745 

to  amine,  736 

dehydrated,  688,  692,  720 

dehydrogenated,   650,    662,   720,    Pd 
669 

hydrogenated,  369 
Benzhydryl  amine,  736 

mercaptan,  745 
Benzidene,  202 
Benzoic  acid  from  aldehyde,  225 

into  aldehyde,  853 

from  benzotrichloride,  320 

decomposed,  830,  834,  839,  840-845 

esterified,  757,  758,  766,  rate  75Sn 

hydrogenated,   Ni    590,   Pd  551,   Pt 
559,  560 

into  ketone,  848-850 

by  oxidation,  257 

sulphonated,  815n,  816 

from  toluene,  150 
Benzoic  esters,  decomp.,  864 

hydrogenated,  471 
Benzolne,  220,  234,  590 

hydrogenated,  391 

Benzonitrile  by  dehydration  of  amine, 
681 

by  diazo  reaction,  605 

from  esters,  871 

hydrogenated,  428 

polymerized,  232 

Benzophenone,     538,    650,     662,    669, 
720,  845,  846,  890 

condensed,  809 

formed,  839,  891,  893,  899 

by  F.  and  C.  syn.,  891,  893,  899 

hydrogenated,    389,     539,     590,    Cu 

523,  Pt  560 

Benzophenone  oxime,  384 
Benzotrichloride,  320 


SUBJECT  INDEX 


371 


Benzoyl-acetone  hydrogenated,  391 
Benzoyl-benzoic  acid,  syn.  of.,  893 
Benzoyl   chloride  in   F.   and   C.   syn., 
893,  899 

hydrogenated,  Pd  575 

into  nitrile,  813 
Benzoyl  peroxide  cat.,  214 
Benzoyl-propionic  acid,  203 
Benzoyl-salicylic  aid.  hydrogenated,  568 
Benzoyl-vanilline  hydrogenated,  568 
Benzyl-acetone  hydrogenated,  389 
Benzyl  alcohol,  549,  560,  715,  729,  740 

from  aldehyde,  225 

into  amine,  734 

cat.  solvent,  38 

condensed,  728 

dehydrated,  688,  714 

dehydrogenated,   C<}O  674,   Cu  657, 
MnO  673 

esterified,  771,  773 

hydrogenated,  369,  465,  538,  593 

oxidised,  249 
Benzyl  amine,  428,  631,  734 

catalyst,  836 

dehydrogenated,  681 

hydrogenated,  470,  496,  560 
Benzyl-aniline,  729 
Benzyl-benzylidene-acetone,  547 
Benzyl  chloride  dechlorinated,  605 

decomposed,  880,  916 

formed,  281,  818,  889 

in  F.  and  C.  syn.,  889 

in  syn.,  899,  901 
Benzyl  cyanide,  605,  871 
Benzyl-cyclohexyl-amine,  739 
Benzyl  formate,  773 
Benzylidene  acetate  formed,  240 
Benzylidene-hydrindone,  799 
Benzylidene-malonic  acid,  804 
Benzyl  mercaptan,  744 
Benzyl-pyridines  syn.,  901 
Beryllia  cat.,  651,  675,  676,  702,  778,  828 

esterific.  cat.,  778 
Betulol  hydrogenated,  570 
Bi-cyclo-octane,  480 
Bi-cyclo-octene  hydrogenated,  480 
Bis-diazoacetic  acid  hydrol.,  332 
Bismuth  oxidised,  269n 
Bleaching  of  oils,  265 
Blue  oxide  of  molybdenum  cat.,  675, 
732,  827 


dehydration  cat.,  791 

mercaptan  cat.,  746 

Blue  oxide  of  tungsten  cat.,  651,  676, 
693,  700,  702,  708,  709,  715,  716, 
732,  825 

dehydration  cat.,  791 

mercaptan  cat.,  746 

preparation  of,  715 
Boric  acid  dec.  esters,  864 

dehydration  cat.,  687 

influence  in  hydrogenation,  944 

oxidation  cat.,  274 

toxic  to  cats.,  115 

Boron  fluoride  polymer,  cat.,  84,  211 
Borneol  from  acetate,  340 

from  camphor,  591,  722 

dehydrated,  714 

dehydrogenated,  661 

esters  of,  340 

oxidised,  257,  260n 
Bornyl  acetate,  340 
Brands  of  hardened  fats  967,  967n 
Brass  cat.,  254n,  670 
Brass  block  furnace,  348 
Brassidic  acid  formed,  184 

into  ketone,  843 
Brochet's  apparatus,  597 
Bromal  cond.,  806 
Bromanilines  red.,  405 
Brombenzene  formed,  292,  293 

hydrogenated,  405,  545 

sulphonated,  815n 

in  syn.,  901,  904 
Brombenzoyl  chloride  in  F.  and  C.  syn., 

893 

Bromides  cats.,  84 
Bromination,  290-293 
Bromine,  cat.,  43 

chlorination  cat.,  279 

elim.,  405,  407,  605 

isomerization  cat.,  182 

toxic  to  cats.,  116,  359 
Bromnaphthalenes  isom.,  199 
Bromnitrobenzenes  hydrogenated,  405, 

512 

Bromstyrene  hydrogenated,  546 
Bromtoluene,  293,  405 
Brucine  hydrogenated,  555 
Butadiene  formed,  726,  784 

polym.,  213 
Butaneal-ol  (1,  3)  formed,  219 


372 


SUBJECT  INDEX 


Butane,  473,  621 
Butanediol  dehydrated,  726 

hydrogenated,  438 
Butanol-one,  438 
Butanone  hydrogenated,  435 
Butylene,  776 

Butyl  alcohol  from  crotonic  aid.,  419, 
567,  801 

dehydrated,  700,  713,  719 

dehydrogenated,  656,  664 

esterified,  771,  773 

oxidised,  249,  268 
sec.  Butyl  alcohol  dehydrated,  713 

dehydrogenated,  665 
tert.  Butyl  alcohol  dehydrated,  713 

esterified,  776 
Butyl-benzene  hydrogenated,  448,  569 

by  hydrogenation,  389,  391 
Butyl  benzoate,  766 
tert.  Butyl  bromide,  200 
Butylene  from  acetylene,  916 

by  dehydration,  670,  696,  713 
Butyl  formate,  773 
tert.  Butyl  isocyanate,  430 
Butyl  mercaptan,  744n 
Butyl-naphthalene  by  hydrog.,  390 
Butyl-phenol  hydrogenated,  459 
Butyric  acid  from  crotonic,  422 

decomposed,  839 

esterified,  771 

into  ketone,  840,  842-844,  846 
Butyric  aldehyde  from  BuOH  by  Ni, 
664 

from  PrCOCl,  575 

from  crot.  aid.,  419,  567 

crotonized,  795 

dec.  by  Pd,  623 

by  oxidation,  249 

polymerized,  223 
Butyric  esters  decomp.,  863,  871 
Butyrolactone  by  hydrogenation,  392 
Butyryl  chloride  hydrogenated,  575 

Cadmium    dehydrogenation    cat.,    674, 

824 

ketone  cat.,  841 
Cadmium  chloride  cat.,  876 
Cadmium  oxide  dehydrogenation  cat., 

674,  676 

dec.  formic  ac.,  539 
ketone  cat.,  841,  849 


Cadmium  sulphate  cat.,  626 

Calcium  carbonate  in  acetone  prep.,  161 

carrier  for  cat.,  127 

catalyst,  98 

ketone  cat.,  161,  838,  839,  849,  857 

to  neut.  oils,  848 

Calcium  hydroxide  toxic  to  cats.,  115 
Calcium  oxide  cat.,  83,  98 

decomp.  hydrocarb.,  911 

ketone  cat.,  840,  849 
Calcium  salts  cats.,  269n 

decomposed,  837 

Calcium  sulphate  cat.,  98,  687,  718 
Camphane,  477,  552,  594,  611,  722 
Camphane  from  borneol,  722 

dehydrogenated,  644 

hydrogenated,  Cu  594,  Ni  477,  591, 

Pd  552,  Pt  570 

Campholide  by  hydrogenation,  392 
Camphor  from  borneol,  260n,  269n,  661 

hydrogenated,  591,  722 

by  oxidation,  257,  260n,  269n 
Camphor  acids,  836 
Camphor-hyrazone  dec.,  611 
Camphoric  acid  by  oxid.,  257 
Camphoric     anhydride     hydrogenated, 

392 

Camphorone  hydrogenated,  421 
Camphor-oxime  hydrogenated,  385 
Cane  sugar  oxidised,  269 
Candelite,  967 

Caoutchouc,  syn.  of,  214,  215 
Caproic  acid  into  aldehyde,  853 

esterified,  771 

into  ketone,  845 
Caproic  aldehyde,  853 
Caproic  esters  decomp.,  871 
Caprylic  acid  into  ketone,  843 
Caprylene  hydrogenated,  414 
Carbamic  chloride  in  F.  and  C.  syn  , 

895 

Carbazol  hydrogenated,  490 
Carbides  in  earth,  928 
Carbimides,  431 

Carbohydrates  hydrogenated,  595 
Carbon    catalyst,    48,    49,    257,    257n, 
687,  700,  811,  828,  911 

cat.  dec.  alcohols,  679 

dehydrogenation  cat.,  638,  679 

hydrogenated,  409,  525,  586 

oxidation  cat.,  257 


SUBJECT  INDEX 


373 


separated,  613 
Carbon  dioxide  eliminated,  831 

hydrogenated,    Co  504,   Cu  508,   Ni 

395,  396,  586,  Pt  533 
Carbon  disulphide  chlorinated,  283 

eliminated  from  ill.  gas,  339,  372 

on  F.  and  C.  syn.  892,  893,  897 

hydrogenated,  372,  492 

hydrolyzed,  339 

negative  cat.,  303 

reduced,  372 

into  thioureas,  630 

toxic  to  cats.,  116 

Carbon  hexachloride  formed,  289,  881 
Carbon  monoxide,   508,   593,   613-617, 
821,  825-828,  866-869,  953 

added,  298 

decomposed,  163,  614 

eliminated,  618-625 

from  formic  acid,  143,  172 

in  F.  and  C.  syn.,  297,  298 

hydrogenated,  540,  Co  504,  Ni  393, 
394,  Pd  536,  Pt  533 

in  hydrogenation,  953 

oxidised,  150,  180a,  248,  251 

source  of  H  in  hydrogenation,  537 

toxic  to  cats.,  116,  1800 
Carbon  suboxide,  873 
Carbon  tetrachloride  added,  242 

formed,    1806,    278,    279,     282-285, 

287 
Carbylamines  hydrogenated,  430,  521 

hydrolyzed,  334 

Carbonyl  chloride  in  F.  and  C.  syn., 
891,  893 

polymerize  aids.,  222 

preparation,  134,  282,  282n 
Carbonyl  group  hydrogenated,  432-442 
Carboxy-camphor  acids,  836 
Carriers  for  cats.,  126,  941,  946 
Carvacrol  hydrogenated,  459 
Carvacrylene,  789 
Carvacryl  ethers,  786,  789 
Carvomenthane,  hydrogenated,  570 
Carvomenthol,  567,  722 
Carvomenthone,  591 
Carvone  hydrogenated,  476,  552,  567, 

591 

Carvotenacetone,  567 
Caryophylene  hydrogenated,  560 
Castor  oil  in  alcoholysis,  341 


hydrogenated,  968 

iodine  no.,  938 
Catalysis,  definition,  1,  3,  4,  140 

at  a  distance,  180.; 

history  of,  4 

mechanism  of,  129-180u 
Catalysts,  amounts  of,  32,  951 

for  cracking,  906,  910-912 

dehydration,  687 

hydrogenation,  598,  941 

life  of,  111,  359,  947 

orienting,  816 

placing  in  tubes,  128 

poisons  for,  112,  113,  116,  359,  946 

preparation,  54-56,  58,  59,  76-78, 
598,  606,  655,  704,  705,  707n, 
861n,  941,  942 

regeneration  of,  947n,  950 
Caucasian  petroleum,  926 
Cellulose  hydrolyzed,  323 
Ceria  in  drying  oils,  266 

ketone  cat.,  849 

oxidation  cat.,  259,  261 

promoter,  1802 
Cerium    compounds    cats.,    153,    264, 

269n,  271 
Charcoal  as  absorbent,  ISQd,  ISQq 

animal  as  carrier,  946 

animal  as  cat.,  282n,  700 

carrier  for,  Ni  598,  941,  946 

catalyst,  828 

chlorination  cat.,  282 

cat.  for  phosgene,  282n 

condenses  gases,  131,  135 

dec.  hydrocarb.,  911 
Chemical  potential,  1800 
Chemical  theory  of  cat.,  145 
Chloracetanilid,  202 
Chloracetates  reduced,  407 
Chloracetic  acid,  280,  281 
Chloral  cond.,  239,  806 

polymer.,  224,  228 
Chloranilines,  512,  632 
Chlorates  oxidisers,  271 

reduced  by  Pd,  165 
Chlorbenzenes  formed,  278,  284,  285, 

404 
sulphonated,  815n 

in  syn.,  904 

Chlorbenzoic  acid  hydrogenated,  545 
in  syn.,  901 


374 


SUBJECT  INDEX 


Chlorbenzoyl  chloride    in    F.    and    C. 

syn.,  893 
w-Chlorbutyl-benzene    in    F.    and    C. 

syn.,  897 

Chlorcaffeine  hydrogenated,  545 
Chlorcinnamic  ac.  hydrogenated,  245 
Chlor-compounds  hydrolyzed,  320 
Chlorcrotonic  acid  hydrogenated,  545 
Chlorcyclo-hexane,  403 
j8-Chlorethyl-benzene    in    F.    and    C. 

syn.,  897 

Chlorides  cats.,  84  et  seq. 
Chlorides  chlorination  cats.,  278 

oxidation  cats.,  263 
Chlorination,  44,  58,  90,  156,  278-289 

of  acetic  acid,  280 

catalysts,  283-285 
Chlorine  absorbed  by  C,  180& 

catalyst,  43 

eliminated,  403,  404,  407,  605 

produced,  103 

toxic  to  cats.,  359,  947 

on  water,  257n 
Chlorketones  produced,  243 
Chlormethyl  ethers  cond.,  818 

in  F.  and  C.  syn.,  889,  899 
Chlor-nitrobenzenes  hydrogenated,  404, 
512 

in  syn.,  901 

Chlor-nitrobenzoic  acid  in  syn.,  901 
Chloroform  cond.,  238 

formed,  629,  879 

in  F.  and  C.  syn.,  890 

negative  cat.,  11,  238 

stabilized,  11 

in  syn.,  890,  903 
cc-Chlorpentyl-benzene    in    F.    and    C. 

syn.,  897 

Chlorphenols  by  reduction,  404 
Chlorpicrin,  180g 
Chlortoluene  hydrogenated,  569 
Cholesterine  hydrogenated  Pt,  565 
Chromic  chloride,  357 
Chromic  oxide,  cat.,  75,  675,  676,  693, 
703,  732,  746,  791,  840,  849 

dehydration  cat.,  702,  791 

dehydrogenation  cat.,  686 

in  drying  oils,  266 

ketone  cat.,  840,  849 

mercaptan  cat.,  746 

mixed  cat.,  702 


oxidation  cat.,  259 

preparation  of,  78 
Cinchonidine  hydrogenated,  Pd  555 
Cinchonine  hydrogenated,   Pd  555,  Pt 

561 

Cinchotine,  555 
Cineol  dehydrogenated,  645 
Cinnamene  hydrogenated,  451 
Cinnamic  acid  esterified,  756,  757 

formed,  107,  246 

hydrogenated,    417,    581,    583,    604, 
Cu  594,  Ni  590,  601,  Ru  580 

by  hydrogenation,  548 
Cinnamic  alcohol  oxidised,  249 
Cinnamic  aldehyde  from  alcohol,  246 

condensed,  799 

hydrogenated,  Pd  546,  Pt  568,  560 

by  oxidation,  249 
Citraconic  acid  hydrogenated,  Pt  558 

isomerized,  183 
Citral  condensed,  800 

from  geraniol,  658 

hydrogenated,  Pd  595,  Pt  567 
Citric  acid  esterified,  756 

retarder,  11 

toxic  to  cats.,  115 
Citronellol,  416 

Class  of  alcohol  determined,  701 
Clay  dehydration  cat.,  99,  700,  702,  717 
Clarifying  solutions,  25  7n 
Clupadonic  acid,  937,  938,  955 

esters  of,  937 
Coal  oxidation  cat.,  257 
Cobalt  on  alcohols,  666 

catalyst,  57,  167,  615 

in  cracking,  906 

decomp.  C2H2,  919,  920,  928 

decomp.  aromat.  hydrocarb.,  921 

decomp.  hydrocarb.,  906,  912 

dehydrogenation  cat.,  637,  651,  652, 
666 

deterioration  of,  500 

hydrogenation  cat.,  344,  499-504,  945 

in  drying  oils,  266 

oxidation  cat.,  254,  258 
Cobalt  carbonyl,  616 
Cobalt  chloride  cat.,  283,  876 
Cobalt  oxide,  oxidation  cat.,  75,  180a, 

259 

Cobalt  soap,  265 
Cocoa  butter,  alcoholysis  of,  341 


SUBJECT  INDEX 


375 


hardened,  966 

iodine  number,  938 
Cocoaimt  oil,  hydrogenated,  939 
Codeine,  hydrogenated,  Pt  572 
Codliver  oil,  hardened,  966 

iodine  number,  938 
Coke  as  catalyst,  48,  257 
Colchicine  hydrogenated,  Pd  555 
Collidines,  686 

Collisions  of  molecules,  180e,  ISO/ 
Colloidal  metals,  preparation  of,  67 
Colloidal  palladium,  544-555,  604 
Colloidal  platinum,  544,  556-561 
Colophene  from  pinene,  216 
Colza  oil,  938 

Complex  rings  hydrogenated,  Pt  571 
Condensation  of  aldehydes,  794-800 

of  ketones,  794-800 
Coniferine  hydrol.,  329 
Coniferyl  alcohol  by  hydrol.,  329 
Contact  process,  180r,  258 
Contra- valencies,  180ft 
Copper    catalyst,    59,    269n,    538-540, 
683,  692,  824,  831,  833-835,  901, 
904,  920-922 

on  alcohols,  142 

colloidal,  72 

in  cracking,  906,  932 

decomp.  C2H2,  913,  916,  917,  920 

decomp.  aldehydes,  621 

decomp.  CO,  615 

decomp.  formic  esters,  867 

decomp.  hydrocarb.,  921 

decomp.  pinene,  922 

dehydrogenates  amines,  681 

dehydrogenation  cat.,  142,  636,  637, 
641,  646,  651-654,  656-663,  680, 
681,  701,  720,  726,  824 

on  diazo-comps.,  606-610 

hydrogenation  cat.,  344,  507-523, 
594,  939,  945 

isomer.  cat.,  208 

oxidation  cat.,  15,  75,  162,  167, 
253,  254,  258 

preparation,  59,  606,  655 
Copper  chloride  cat.,  635 
Copper  oxide  cat.,  259,  269n 
Copper  powder  cat.,  606-610,  655 
Copper  salts  in  nitration,  269n 

in  oxidation,  271 
Copper  sulphate  cat.,  240,  272,  725 


in  Deacon's  proc.,  103 
Cottonseed  oil,  iodine  number,  938 

hydrogenated,  587,  965,  967n 
Coumanic  acid  dec.,  835 
Cracking,  906,  910-912,  929-936 

by  A1C13,  929-931,  935 

by  cats.,  910-912,  932,  934 

discovery,  906 

with  oxide  cats.,  934 
Cresol  ethers  hydrogenated,  494 
Cresols  with  aldehydes,  792 

ethers  of,  386,  785,  786,  789 

formed,  386,  645,  660 

hydrogenated,  457,  464 

by  oxidation,  263 
Cresyl-carvacryl  ether,  788 
Cresyl-diamines  by  hydrogenation,  380 
Cresyl  oxides,  785 
Cresyl-propanes  hydrogenated,  415 
Crisco,  967n 
Crotonic  acid  into  aldehyde,  853 

esterified,  756,  771 

hydrogenated,  422,  Pd  546,  Pt  558 
Crotonic  aldehyde,  307,  794-796,  801 

condensed,  796 

formed,  52,  219,  308,  310 

hydrogenated,  419,  Pt  567 
Crotonization,  81,  89,  107,  794-800 

of  aldehydes,  795 

of  ketones,  797 
Crotonylene  polym.,  212 
Cumene,  644 
Cuminic  aldehyde  by  oxidation,  249 

polymerized,  220 
Cuminoine,  220 
Cuminyl  alcohol  oxid.,  249 
Cuprene,  518,  916-918 
Cupric  hydroxide  purif .  of  oils,  948 
Cuprous  bromide  cat.,  608,  611,  633 

in  diazo  reaction,  91 

prep.,  608 

Cuprous  chloride  cat.,  298,   611,  633, 
879,  901 

in  diazo  reaction,  91 
Cuprous  iodide  cat.,  611,  901 

in  diazo  reaction,  91 
Cuprous  oxide  in  diazo.,  91 
Cuprous  salts  cats.,  611,  633 

in  diazo  reaction,  606-610 
Cyanethine,  232 
Cyanides  cats.,  95 


376 


SUBJECT  INDEX 


Cyanogen  hydrated,  312 
Cyaphenine,  232 
Cyclic  acids  dec.,  830 
Cyclic  hydrocarb.  dec.,  921 

polym.,  216 
Cyclic  ketones,  611 
Cyclic  ketoximes,  205 
Cyclization,  82,  194 
Cyclo-aliphatic  ethers,  494 
Cycle-butane,  473 
Cyclobutene  hydrogenated,  473 
Cyclobutene  bromide,  293 
Cycloheptane,  197,  479,  649 
Cyclohexadienes  dehydrogenated,  643 
Cyclohexadiols,  461 
Cyclo-hexadione,  874 
Cyclo-hexamethylene  ring,  475 
Cyclohexane,  445,  452,  466,  468,  469, 
471-475,   497,   534,  560,  587,  589, 
611,  643 

decomp.,  921 

dehydrogenated,  Fe  593,  Ni  641 

formed,   26,   55,   113,  361,  388,  389, 
403 

oxidised,  251 

prepared,  446 

purified,  446 

Cyclohexane  alcohols,  698,  737 
Cyclohexane    hydrocarb.     dehydrogen- 
ated, 641 

formed,  389 

Cyclohexane  petroleums  cracked,  934 
Cyclohexanol,  30,   120,  443,  460,  461, 
560,  569,  589,  603,  739,  741 

into  amine,  737 

dehydrated,  714 

dehydrogenated,  642,  660 
Cyclohexanol  homologs  dehydrogenated, 

642 
Cyclohexanone,  456,  560,  642,  660 

crotonized,  797 

hydrogenated,  436,  567 

hydrazone,  611 

oxime  hydrogenated,  385 
Cyclohexatriol,  462 

Cyclohexene,  456,  475,   515,  628,  643, 
698,  714 

dehydrogenated,  643 

hydrogenated,  587 

Cyclohexene  acetic  acid  hydrogenated, 
476 


Cyclohexendiol  ether,  443 
Cyclohexenes  by  dehydration,  698 

dehydrogenated,  643 
Cyclohexanol  by  oxidation,  251 
Cyclohexenone  hydrogenated,  Pd  552 
Cyclohexyl-acetic  acid,  471,  476 
Cyclohexyl     alcohols     dehydrogenated, 

714,  717 

esterified,  757,  766 
Cyclohexyl-amine,  466,  469,  497,  560, 

569,  737,  739 
dehydrogenated,  Ni  642 
by  hydrogenation,  378,  385 
Cyclohexyl-amines,  739 
Cyclohexyl-aniline,  466,  469,  642 
Cyclohexyl  benzoate,  766 
Cyclohexyl  chlorides  decomp.,  876 

in  F.  and  C.  syn.,  889 
Cyclohexyl-cy  clohexene     hydrogenated , 

475 

Cyclohexyl-diethyl-amine,  468 
Cyclohexyl-ethyl-amine,  468 
Cyclohexyl-heptane  by  hydrogenation, 

414 

Cyclohexyl  mercaptan,  628,  745 
Cyclohexyl-methyl-amine,  468 
Cyclohexyl  oxide,  589 
Cyclohexyl  piperidine,  741 
Cyclohexyl-propionic    acid,    471,    580 

581,  590 

Cyclohexyl-propyl  alcohol,  560 
Cyclohexyl  sulphide,  628 
Cyclo-oetadiene,  480 
Cyclo-octane  dec.  Ni,  197 

by  hydrogenation,  480,  571 
Cyclo-octanone,  571 
Cyclo-octatetrene    hydrogenated,     535, 

571 

Cyclo-octatriene  hydrogenated,  571 
Cyclo-octenone  hydrogenated,  571 
Cyclo-paraffine     oximes    hydrogenated, 

385 

Cyclopentadiene  hydrogenated,  474 
Cyclopentane,  436,  474,  649 
Cyclopentane-carbonic  acid,  649 
Cyclopentanol,  436 
Cyclopentanone,  874 
hydrogenated,  436,  567 
oxime  hydrogenated,  385 
Cyclopentyl-amines  by  hydrogenation, 
385 


SUBJECT  INDEX 


377 


Cyclopental-benzene  by  F.  and  C.  syn., 

897 

Cyclopentyl  chlorides  dec.,  876 
Cyclopentyl-cyclopentanone,  436 
Cyclopropane  hydrogenated,  472 
Cyclopropane  ring  dec.,  193 
Cymene  dec.  by  AlCla,  930 

by  dehydrogenation,  644,  645 

hydrogenated,  448 

from  pinene,  922 
Cymenes  by  hydrogenation,  369,  415 

Deacon's  process,  103,  1806,  257n 
Decahydro-acenaphthene,  563 
Decahydro-anthracene,  592 
Decahydro-fluorene,  454 

dehydrogenated,  642 
Decahydro-naphthalene,  481,  553,  571, 

592,  594 

Decahydro-naphthols,  481,  592,  714 
Decahydro-quinaldine,  488 
Decahydro-quinoline,  488,  555,  561,  592 
Decane,  595 
Decanol,  595 

Decarbonization  of  CO,  614 
Decomposition  of  acids,  820-856 
Decomposition  of  esters,  858-872 
Decomposition  and  cond.  of  hydrocarb., 

905-936 

Decompositions  by  Ni,  493 
Decyclizations,  193 

Dehydration,    687-727,    728-784,    785- 
816,  825 

of  alcohols,  138,  169,  688-727 

of  alcohols  with  acids,  747 

of  alcohol  with  aids.,  779 

of  alcohols  with  amines,  729 

of  alcohols  with  ammonia,  729 

of  alcohols  with  hydrocarb.,  728 

of  alcohols  with  hydrogen  sulphide, 
743 

of  alcohols  with  ketones,  779 

of  aldehydes,  794 

of  aids,  with  ammonia,  807 

of  aids,  with  hydrogen  sulphide,  810 

of  aids,  with  ketones,  798 

by  alumina,  713 

of  amides,  811 

apparatus,  717 

of  benzhydrol,  720 

by  beryllia,  778 


by  blue  oxide  of  tungsten,  715 
catalysts,  538,  651,  675,  687,  702,  825 
in  gas  phase,  693,  694,  700-727,  731, 

801 

of  glycerine,  760 
with  hydrogenation,  721,  722 
by  iodine,  699 
of  ketones,  797 
in  liquid  medium,  691,  692,  695-699, 

729 

by  metal  oxides,  702,  763 
by  mineral  acids,  696,  749 
of  oximes,  814 
of  phenols,  785-793 
of  phenols  with  alcohols,  789 
of  phenols  with  amides,  790 
of  phenols  with  hydrogen  sulphide, 

791 

of  poly-alcohols,  723,  727 
with  ring  formation,  727 
theory  of,  169,  689 
by  thoria,  716 
by  titania,  767  et  seq. 
by  zinc  chloride,  698 
Dehydroacetic  acid  formed,  387 
Dehydrogenation,  15,  63&-6S6,  807-809, 

824,  910,  921 
of  alcohols,  31,  650-679 
by  aluminum  chloride,  685 
of  amines,  681,  682 
of  anthracene  hydrides,  642 
apparatus,  654 
by  cadmium  oxide,  674 
by  carbon,  679 

catalysts,  636-338,  651,  675,  702,  824 
classification,  638 
by  cobalt,  666 
by  copper,  653-663 
in  cracking,  910 
of  cyclohexane  comps.,  641 
history  of,  636 
of  hydro-aromatic  hydrocarb.,   640- 

649 

of  hydrocarbons,  639-649,  921 
of    hydrocyclic     hydrocarbons,     640 

et  aeq. 

by  iron,  667 

by  manganous  oxide,  672 
of  methyl  alcohol,  676 
of  naphthalene  hydrides,  642 
by  nickel,  664,  684 


378 


SUBJECT  INDEX 


by  oxides,  672-675,  686 

by  palladium,  649,  669 

of  piperidine,  647 

by  platinum,  668 

of  poly-alcohols,  680 

of  second,  amines,  682 

by  stannous  oxide,  673 

of  terpenes,  643  et  seq. 

of  tertiary  amines,  682 

theory  of,  168 

by  various  oxides,  675 

by  zinc,  670 

Dehydromucic  acid,  727 
Dekalin,  481n 
Depolymerization,  234,  235 
Desoxybenzoine  hydrogenated,  389 
Dextrine  by  hydrolysis,  326 

hydrolyzed,  323,  326 
Diacetonitrile,  230 

Diacetonyl  alcohol  dehydrated,  698,  699 
Diacetyl  hydrogenated,  438 
Diacetyl-dihydromorphine,  555 
Diacetyl-morphine     hydrogenated,     Pd 

555,  Pt  561 

Diamines  by  hydrogenation,  380 
Diamylene  formed,  210,  211 
Diastase,  758 
Diazoacetic  ester,  12 
Diazobenzene,  59,  206,  606,  607 
Diazo-compounds  decomp.,  59,  606-610 

hydrogenated,  497 
Dibasic  acid  chlorides  in  F.  and  C.  syn., 

893 
Dibasic  acids  decomposed,  855 

esters  of  dec.,  872-874 
Dibenzal-acetone,  798 
Dibenzoyl  hydrogenated,  391 
Dibenzyl  hydrogenated,  452,  589 

by  hydrogenation,  389,  391,  415,  548, 

590,  593 

Dibenzyl-acetone,  547 
Dibenzyl-amine,  428,  734 
Dibenzyl-aniline,  729 
Dibenzyl-benzene,  728 
Dibenzylidene-acetone      hydrogenated, 

547 

Dibenzyl  ketone  hydrogenated,  455 
Dibromethylene  in  F.  and  C.  syn,  890 
Dibrom-succinic  acid,  182 
Dibutyl  ketone,  844 
Dichloracetyl  chloride  dec.,  625 


Dichlorbenzenes,  404 
Dichlorcyclohexane  dec.,  876 
Dichlorethylene,  242 
Dicyanamide  formed,  233 
Dicyanides  hydrogenated,  429 
Dicyclohexyl,  452,  475,  589 
Dicyclohexyl-amine,  466,  469,  497,  569, 
590,  642,  739 

by  hydrogenation,  385,  739 
Dicyclohexyl-butanes,  452 
Dicyclohexyl-ethanes,  452,  589 
Dicyclohexyl-methane,  389,  453,  560 
Dicyclohexyl-phenyl-methane,  453 
Dicyclohexyl-propane,  455 
Dicyclononane,  454 
Diethyl-allylene  formed,  50,  192 
Diethyl-amine  by  hydrogenation,  377, 

383,  386,  427 

Diethyl-amine.  HC1  catalyst,  783 
Diethyl-aniline  dec.  Ni,  634 

formed,  729 

hydrogenated,  468 
Diethyl-benzene,  888,  930 
Diethyl-carbinol  into  amine,  735 
Diethyl-diphenyl  formed,  241 
Diethylene    compounds    hydrogenated, 

547 

Diethylenic  acids,  937 
Diethyl  ketone  formed,  838 

hydrogenated,  435,  567 
Diethyl-phenol  hydrogenated,  459 
Dihalogen    compounds   in    F.   and    C. 

syn.,  890 
Diheptene,  519 

Dihexahydrobenzyl-amine,  470 
Dihydrobenzene,  723,  876 
Dihydrobrucine,  555 
Dihydrocamphene,  570 
Dihydrocamphorone,  hydrogenated,  390 

by  hydrogenation,  421 
Dihydrocinchonidine,  555 
Dihydrocitronellol    by    hydrogenation, 

416 

Dihydrocodeine,  572 
Dihydro-dimethyl-anthracene,  890 
Dihydro-eugenol,  577 
Dihydro-indol,  571 
Dihydro-ionones,  554 
Dihydrolimonene,  517,  591 
Dihydromorphine     by     hydrogenation, 
572 


SUBJECT  INDEX 


379 


by  oxidation,  268 
Dihydronaphthalene,  571,  931 
Dihydrophytol,  565 
Dihydroquinine,  572 
Dihydropinene,  477,  570 
Dihydrophenanthrene,  484,  571,  592 
Dihydrophorone,  547 
Dihydrosafrol,  418,  565,  590 
Dihydrostrychnine,  555 
Dihydrotetrazines  isom.,  201 
Dihydroxy-acetone,  237,  246,  268 
Dihydroxy-diphenyl-amine,  632 
Di-isoamyl-amine,  682,  733 
Di-isobutyl-carbinol,  549,  567 
Di-isobutyl  ketone,  435,  567,  840 

hydrogenated,  435 
Di-isopropyl-amine,  735 
Di-isopropyl-benzene  from  cymene,  930 
Di-isopropyl  ketone  formed,  844 

hydrogenated,  435 
Diketones  by  dehydrogenation,  663 

by  F.  and  C.  syn.,  893 

hydrogenated,  391,  438-440 
Dimethyl-acetylene  formed,  192 
Dimethyl-acrylic     acid     hydrogenated, 

417 

Dimethyl-allene  formed,  192 
Dimethyl-allyl-carbinol     hydrogenated, 

587 

Dimethyl-amine,  377,  430 
Dimethyl-aniline,  468,  729,  740 

dec.  Ni,  634 

oxidised,  256 

Dimethyl-benzaldehyde,  298 
Dimethyl-butadiene,  726 
Dimethyl-butyl-phenol,  459 
Dimethyl-cyclohexane,    197,    449,    475, 
480 

dehydrogenated,  Ni  641 
Dimethyl-cyclohexanols,  458,  660,  714 
Dimethyl-cyclohexene    by    dehydration 
714 

hydrogenated,  475 
Dimethyl-cyclohexyl-amine,  467 
Dimethyl-cyclopentyl-pentanones,  436 
Dimethyl-diethyl-butine-diol,  548 
Dimethyl-diphenyl-butine-diol,  548,  566 
Dimethyl-diphenyl-methane    hydrogen- 
ated, 452 
Dimethyl-ethyl-carbinol  esterified,  757 

formed,  210,  306 


Dimethylene-pentane  hydrogenated,  414 
Dimethyl-heptane    by    hydrogenation, 

414 

Dimethyl-hexine  hydrogenated  Pd,  548 
Dimethyl-hexine-diol  hydrogenated,  566 
Dimethyl-indol,  490,  633 
Dimethyl-isobutyl-cyclohexane,  449 
Dime  thy  1-ketazine  isom.,  196 
Dimethyl-methylene-cyclopropane     hy- 

drog.,  472 

Dimethyl-octane,  415,  567 
Dimethyl-octanol,  416,  567 
Dimethyl-octadieneol,  416 
Dimethyl-octatriene  hydrogenated,  415 
Dimethyl-octene-diol  hydrogenated,  548 
Dimethyl-pentane-thiol,  745 
Dimethyl-phenols  hydrogenated,  458 
Dimethyl-propyl-carbinol,  587 
Dimethyl-quinoline,  491 
Dimethyl-toluidines,  684,  740 
Dinaphthyl  dehydrogenated,  685 
Dinaphthyl-amine,  632 
Dinitrobenzenes,  269n,  512 
Dinitro-compounds  hydrogenated,  380 
Dinitro-toluenes  hydrogenated,  380 
Dipentene  depolymerized,  235 

formed,  198 
Diphenols,  ethers  of  syn.,  904 

reduced,  370 
Diphenyl  formed,  907 

in  F.and  C.  syn.,  896 

hydrogenated,  452,  589 

by  hydrogenation,  403,  406 
Diphenyl-amine  from  aniline,  466 

by  dehydration,  642 

hydrogenated,  469,  590 

stabilizer,  13 

sulphurized,  296 

syn.  of,  901 

Diphenyl-anthrone  syn.  of,  893 
Diphenyl-benzene  formed,  907 
Diphenyl-butadione  by  F.  and  C.  syn., 

893 

Diphenyl-butanes     by     hydrogenation, 
520,  548 

hydrogenated,  452 
Diphenyl-butadiene,  548 
Diphenyl-butenes  hydrogenated,  415 
Diphenyl-butine-diol  hydrogenated,  548 
Diphenyl-cyclopropane,  611 
Diphenyl-decadiene  hydrogenated,  545 


380 


SUBJECT  INDEX 


Diphenyl-decane,  546 
Diphenyl-diacetylene  hydrogenated,  548 
Diphenylene  oxides,  787 
Diphenyl-ethanes  formed,  241,  728,  890 

by  hydrogenation,  391,  415,  721,  728 

hydrogenated,  452 
Diphenyl-ethylene  formed,  890 

hydrogenated,  415,  515 
Diphenyl-methane,  369,  389,  523,  538, 

539,  590,  662,  720,  728,  806 
Diphenyl-pentanes  hydrogenated,  452 
Diphenyl-pentens  hydrogenated,  415 
Diphenyl-propane  formed,  728 

by  hydrogenation,  389,  415 

hydrogenated,  452 

Diphenyl-propenes  hydrogenated,  415 
Diphenyl  sulphide,  629 
Diphenyl  thio-urea,  630 
Diphenyl-pyrazoline  dec.,  612 
Diphenyl  urea,  495 
Diphthalid  formed,  107 
Dipiperonal-acetone  hydrogenated,  565 
Dipropionic  nitrile,  231 
Dipropyl-amine,  427,  733 
Dipropyl-carbinol  into  amine,  735 
Dipropyl  ketone  formed,  843 

hydrogenated,  Ft  567 
Dipropylene  polym.,  213 
Divinyl  polym.,  213 

Dodecahydro-anthracene  by  hydrogena- 
tion, 29,  363 

Dodecahydro-phenanthrenedehydrogen- 
ated,  642,  646 

by  hydrogenation,  484 
Doremol  hydrogenated,  Pt  570 
Doremone  hydrogenated,  Pt  570 
Drying    hydrogen    for    hydrogenation, 

949 

Drying  oils,  266 
Dulcite,  588,  595 
Duodecene  polym.,  210 
Duratol,  967 
Durene  hydrogenated,  Pt  569 

Egg  lecithine  hydrogenated,  Pd  555 
Elaidic  acid  formed,  82,  184 

esters  of,  937 

hydrogenated,  422 

into  ketone,  843 
Electric  heating,  349 
Electrolytic  dissociation,  175 


Elimination  of  ammonia,  631-633 

of  aniline,  634 

of  carbon,  613 

of  carbon  monoxide,  618-625 

of  halogens,  605 

of  hydrogen  sulphide,  626-629 

of  nitrogen,  606-610 
Ellis's  apparatus,  962 
Emulsine,  18,  327,  329 
Enzymes,  180s 
Equilibrium  in  alcoholysis,  340n 

shifted,  180s 

Erdmann's  apparatus,  958 
Erucic  acid,  184 

esters  of,  937 
Erythrol  formed,  83 
Esterification,  747-778 

by  acid  anhydrides,  761 

of  benzoic  acid,  758 

by  beryllia,  778 

catalytic,  17,  747-778 

of  formic  acid,  773 

in  gas  phase,  762-777 

of  glycerine,  760 

limits,  21,  750-752,  767-770 

in  liquid  phase,  748-761 

mass  law,  770 

rates,  775 

theory  of,  177,  752,  763 

by  titania,  767 

velocity,  747,  774,  777 
Esters  from  aldehydes,  226-228 

with  ammonia,  871 

as  catalysts,  104 

condensed,  803 

decomposed,  180n,  858-874 

formed,  75,  170,  175,  226-228 

hydrogenated,  417 

hydrolyzed,  83,    170,    313-316,   319, 
321,  337 

saponified,  175,  305,  337 
Ethane,  423,  518,  526,  527,  546,  558, 
601,  605,  620,  631,  665,  709 

from  acetylene,  26,  914 

decomp  by  heat,  911 

decomp.  by  Mg,  920 

from  ethylene,  912 

formed,  409 

by  hydrogenation,  26,  342,  377,  412, 

413,  912,  914 
Ether  cond.  with  benzene,  817 


SUBJECT  INDEX 


381 


decomp.,  180m,  338 

formed,  169,  1800,  690,  764,  872 

in  Grignard  reagent,  6 

oxidised,  254 

process,  159,  691 
Ethers,  catalysts,  104 

decomp.,  180m,  321,  338,  494 

formed,  169,  690,  764,  872 

hydrogenated,  418 
Ethoxy-cyclohexane,  464 
Ethyl  acetate  from  aldehyde,  228 

catalyst,  304,  605 

decomp.,  ISO/,  18(K,  180n,  858,  861, 
861n,  871 

formed,  228,  407,  749 

hydrolyzed,  313,  316,  319 

neg.  cat.,  11,  303 

Ethyl  acetoacetate  hydrogenated,  387 
Ethyl-acetylene,  192 
Ethyl  alcohol,  680,  742 

into  acetal,  780,  783 

into  acetol,  783 

into  amines,  732 

catalytic  solvent,  38 

decomposed,  650,  679 

dehydrated,  688,  691,  694,  696,  700, 
702,  709,  713,  716-719 

dehydrogenated,  538,  656,  667,  CdO 
674,  MnO  672,  Ni  664,  Pt  668, 
SnO  673,  Zn  670 

esterified,  750,  770,  771,  773 

hydrogenation  agent,  538 

oxidised,  150,  1806,  249,  254,  257,  260, 

268 

Ethyl  adipate  dec.,  874 
Ethyl-am ine  cat.  prep.,  732 

con.  agent,  804 

dec.  by  Ni,  631 

hydrochloride  catalyst,  783 

by  hydrogenation,  377,  382,  386,  510 

oxidised,  256,  268 
Ethyl-aniline  dec.,  634 

hydrogenated,  468 

prep.,  729 

Ethyl-benzene,  451,  516,  520,  538,  539, 
546,  548,  560,  641,  657,  728 

decomp.,  888,  930 

formed,  362,  369,  389,  415,  817,  888, 
890 

hydrogenated,  362,  448,  534 

by  hydrogenation,  362,  369,  389,  415 


Ethyl  benzoate,  744n,  749,  754,  755,  766 

dec.,  858,  864,  871 

hydrolyzed,  316,  319 
Ethyl  bromide  formed,  104 
Ethyl  bromacetate  reduced,  407 
Ethyl-tert-butyl-benzene,  389 
Ethyl-tert-butyl  ether,  691 
Ethyl  butyrate  dec.,  858 

by  hydrogenation,  387 
Ethyl  caproate  dec.,  861,  862 
Ethyl  carbylamine  hydrogenated,  430 
Ethyl  chloracetate  red.,  407 
Ethyl  chloride  chlorinated,  282 

by  F.  and  C.  reaction,  888 
Ethyl  cinnamate  hydrogenated,  601 
Ethyl  cyanide  catalyst,  108,  605 

hydrogenated,  427 

Ethyl-cyclohexane  dehydrogenated,   Ni 
641 

by  hydrogenation,  362,  448,  451,  452, 

455,  516,  520,  568,  569 
Ethyl-cyclopropane,  193 
Ethyl-diphenyl  formed,  241 
Ethylene,  423,  527,  548,  620,  626,  631, 
634,  650,  670,  686,  689,  691,  696, 
700,  708,  709,  713,  716,  726,  732, 
864,  871 

cond.  with  benzene,  241 

cond.  by  sulphuric  acid,  159 

dec.,  637,  912,  920,  Co  912,  Fe  912, 
Mg  920,  Ni  413,  Pt  912 

formed,  78,  1800,  873,  914 

hydrogenated,  Co  500,  Cu  515,  Ni  413, 
601,  Pd  546,  Pt  526,  558 

manufacture,  180A,  689n,  71 7n 

oxidised,  1806 

polymerized,  211 

preparation,  696n 
Ethylene  bonds  hydrogenated,  939 
Ethylene  compounds  hydrated,  306 

hydrogenated,  412-422,  587,  Co  500, 
Cu  515,  594,  Fe  506,  Ni  601,  Pd  546, 
577,  Pt  526,  558,  565 
Ethylene  chloride  in  F.  and  C.  syn.,  890 

cyanide  hydrogenated,  429 
Ethylene  hydrocarbons  formed,  48,  86, 
681,  682 

in  F.  and  C.  syn.,  90,  241 

hydrogenated,  Co  500,  Cu  515,  Fe  506 

polymerized,  210 
Ethylene  oxides  hydrogenated,  443 


382 


SUBJECT  INDEX 


isomerized,  200 
Ethylenic  acids,  937 
Ethylenic  chlorides,  243 
Ethyl  ether,  694,  689,  713 

cat.,  605 

formed,  873 

hydrogenated,  494 

prepared,  691 
Ethyl  formate,  773,  866 

dec.,  866 

hydrolyzed,  316 
Ethyl  glutarate  dec.,  874 
Ethyl  hexahydrobenzoate,  471,  476 
Ethylidene  chloride  in  F.  and  C.  syn.,  890 
Ethyl  iodide  cat.,  299 

in  Grignard  reaction,  302 

in  syn.,  605,  901 
Ethyl-isoamyl-amine,  738 
Ethyl-isoamyl  ether,  691 
Ethyl-isobutyl  ether,  691 
Ethyl  isobutyrate,  316,  319 
Ethyl  isovalerate,  417 
Ethyl  malonate  dec.,  783 
Ethyl  mercaptan,  626,  744 
Ethyl-methyl-hexene  hydrogenated,  414 
Ethyl-naphthalenes   by  hydrogenation, 

390 

Ethyl  naphthoates  to  nitriles,  871 
Ethyl  nitrate  cond.,  819 
Ethyl  nitrite  as  cat.,  104,  207 

hydrogenated,  382 
Ethyl  oleate  hydrogenated,  565 
Ethyl  ortho-formate,  783 
Ethyl  oxalate  as  cat.,  104 

dec.,  873 

Ethyl  phenyl-acetate  dec.,  871 
Ethyl-phenyl  carbinol,  728 
Ethyl-phenyl  ether,  789 
Ethyl  propionate  dec.,  858 
Ethyl-propyl  ether,  691 
Ethyl-pyridines  syn.,  901 
Ethyl-pyrrol,  742 
Ethyl  stearate  dec.,  858 

by  hydrogenation,  565 
Ethyl  succinate  dec.,  873,  874 
Ethyl  sulphide,  626 
Ethyl  terephthalate,  590 
Ethyl  tetrahydrobenzoate,  476 
Ethyl  toluate,  590 
Ethyl-toluidines,  489 
Ethyl-trimethylene  hydrogenated,  472 


by  hydrogenation,  577 
Ethyl  valerate  dec.,  864 

sapon.,  316,  319 

Ethyl  vanilline  hydrogenated,  568 
Eucalyptol  dehydrogenated,  645 
Eucarvone  hydrogenated,  552 
Eudesmene  hydrogenated,  570 
Eugenol  hydrogenated,  Ni  590,  603,  Pd 
577,  Pt  565,  569 

isom.,  191 
Eugenol  methyl  ether  hydrogenated,  590 

Fairco,  967n 

Farnesol  hydrogenated,  570 

Fats  alcoholized,  341 

hydrogenated,  542,  937-969 

saponified,  314,  317 
Fatty  acids,  effect  on  Ni,  948 

by  hydrol.,  314,  315,  318 
Fenchane,  611,  722 
Fenchone,  611 

Fenchyl  alcohol  dehydrated,  722 
Ferments,  soluble,  18 
Ferric  chloride  acetal  cat.,  781,  783 

catalyst,  687,  843,  849,  878 

chlorination  cat.,  285,  285n 

cond.  cat.,  902 

in  F.  and  C.  syn.,  899,  900 
Ferric  oxide  dehydrogenation  cat.,  677, 
686 

ketone  cat.,  843,  849 

mixed  cat.,  702 
Ferric  sulphate  cat.,  725 
Ferrous  carbonate  chlorination  cat.,  285 
Ferrous  chloride  cat.,  876,  954 

in  F.  and  C.  syn.,  899 
Ferrous  oxide  cat.,  180j,  827 

ketone  cat.,  843,  849 
Ferulene  hydrogenated,  570 
Fibrine  cat.,  110 
Fish  oils,  effect  on  cat.,  947 

hydrogenated,  939,  967n 
Fittig  syn.,  11, 
Flake  white,  967n 
Fluorides  cats.,  841 
Fluorene  by  dehydrogenation,  642 

in  F.  and  C.  syn.,  896 

hydrogenated,  454 

Formaldehyde,  73,  236,  562,  656,  664, 
672,  674,  676,  678,  821,  825,  826, 
851,  870 


SUBJECT  INDEX 


383 


catalyst,  269n 

dec.,  Cu  621,  Fe2O8  677,  Pd  623 

into  ester,  225,  228 

formed,  866,  871 

hydrogenated,  432 

by  oxidation,  249,  252-254,  256 

with  phenols,  792 

preparation,  249,  252-254 

into  sugars,  221 
Formates,  851 

Formic  acid,  64,  621,  839,  851,  852,  855, 
866 

decomp.,  99,  143,  172,  1800,  624,  820- 
828 

esterified,  773 

hydrogenating  agent,  537,  539,  604 

by  oxidation,  249 

oxidised,  246 

syn.  of,  574 

toxic  to  Pt  black,  117 
Formic  esters  dec.,  624,  866-870 
Form  of  metals,  41,  53-55,  76-80 
Formyl  chloride,  298 
Fouling  of  catalysts,  118-120,  122,  932 
Friedel  and  Crafts  synthesis,  33,  87-89, 
157,  173,  174,  241,  241n,  297,  298, 
883-900 

catalysts  for,  899,  900 

catalytic  nature  of,  898 

complications,  885 

cyclic  compounds,  896-898 

with  diphenyl,  889 

with  ethylene  hydrocarb.,  241 

isomerizations  in,  888 

of  ketones,  891-894 

mechanism  of,  898 

method  of  operating,  884,  892 

with  naphthalene,  889 

results  of,  889 

reversed,  887 
Fructose,  186,  324 
Fumaric  acid  esterified,  756 

esters  from  maleic,  182 

hydrogenated,  Pd  546 

isom.,  182 

from  maleic,  182 
Furfural  cond.,  686 

decom.,  Ni  620 

formed,  727 

hydrogenated,  434 

oxidised,  268 


Furfurane,  620 

Furfurane-dicarbonic  acid,  727 
Furfurane  rings,  727 
Furfurome  formed,  220 
Furfuryl  alcohol,  371,  434 
Furfuryl-ethyl    carbinol    hydrogenated, 
487 

Gaidic  acid  formed,  184 
Galactobiose,  18 
Galactose,  18,  186,  188 

hydrogenated,  Ni  588,  Pd  595 

by  oxidation,  268 
Galician  petroleum,  927 
Galtose  formed,  186 
Gases  condensed  by  metal  powders,  135 

in  porous  bodies,  131,  132,  134 
Gases  from  cracking,  909 
Gasoline  by  cracking,  906,  932-936 
Geometrical  isomers,  182 
Geraniol  dehydrogenated,  658 

hydrogenated,  Ni  416,  601,  Pd  595, 

Pt  565 

Glass  powder  as  cat.,  811,  827,  828 
Gluconic  acid,  187 
Glucose  hydrogenated,  Ni  588,  Pd  595 

by  hydrolysis,  324-329 

isomerized,  186 

multirotation  of,  188 
Glucosides  dec.,  18,  175 

hydrolyzed,  305,  327-330 

syn.,  15,  18,  793 

Glutaryl  chloride  in  F.  and  C.  syn.,  893 
Gly eerie  aldehyde  cond.,  237 

formed,  236,  246,  268,  680 

by  oxidation,  268 
Glycerides  saturated,  939 
Glycerine  acetylated,  89 

by  alcoholysis,  340,  341 

dec.  to  formic  acid,  855 

dehydrated,  725 

dehydrogenated,  680 

esterified,  757,  760,  761 

esters  of,  340,  937 

by  hydrolysis,  314,  318 

oxidised,  246,  249 
Glycol  dehydrated,  724 

oxidised,  249,  268 
Glycolic  acid  esterified,  756 
Glycolic  aldehyde  by  oxid.,  249,  268 
Glyoxal  by  oxid.,  249,  268 


384 


SUBJECT  INDEX 


Gold,  absorption  of  O2  by,  137 

catalyst,  66 

colloid,  70,  72 

dehydrogenation  cat.,  637 

oxidation  cat.,  252,  254 
Gold  chloride,  chlorination  cat.,  283 
Goose  fat,  938 
Graphite  catalyst,  702,  717,  911 

formation,  180a 
Grease  cat.  poison,  180o 
Greenwich  gas  works,  373 
Grignard  reaction,  44,  104,  300-302 
Guaiacol  hydrogenated,  Ni  589 
Gulose,  186 
Gum  arabic,  546,  561 
Gunpowder  dec.,  8 

Halides,  300 

Halogenated  alcohols  dec.,  876 
Halogens  eliminated  by  hydrogenation, 
403-407,  545,  605 

toxic  to  catalysts,  112-114 
Hardened  oils  as  foods,  967n,  969 

trade  names  of,  967 
Hardening  of  fats,  577 

of  oils,  937-969 
Heavy  hydrocarbons  cracked,  932 

by  cracking,  906,  936 
Heavy  oils  by  cracking,  906,  936 
Helicine  hydrolyzed,  328 
Helleborine,  330 
Heptachlorpropane  decom.,  879,  357 

formed,  242,  625,  903 
Heptachlortoluene  formed,  287 
Hepta-isobutanal  formed,  224 
Heptaldehyde  cond.,  795 

crotonized,  795 

hydrogenated,  559 

prepared,  853 

Heptaldoxime  hydrogenated,  383 
Heptamethylene  ring  hydrogenated,  479 
Heptane  by  cracking,  936 

by  hydrogenation,  519 
Heptane-thiol,  745 
Heptane  hydrated,  306,  519 
Heptine  hydrogenated,  425,  519 
Heptoic  acid  into  aldehyde,  853 

into  ketone,  845 
Heptoic  aldehyde,  664 
Heptyl  alcohol  dehydrogenated,  664 

by  hydrogenation,  559 


Heptyl-amine  by  hydrogenation,  383 
Heterogeneous  systems,  7,  34 
Hexachlorbenzene,  284 
Hexachlorethane,  289 
Hexachlorpropane,  242 
Hexachlortoluene,  287 
Hexadienal,  796,  801 
Hexahydro-acetophenone,  476 
Hexahydro-anisol,  589 
Hexahydro-anthrone  hydrogenated,  390 
Hexahydro-benzoic  acid,  471,  476,  551, 
560,  569,  590 

dehydrogenated,  649 

esters  of,  471,  649 
Hexahydro-benzyl-amine,  470 
Hexahydro-benzyl-aniline,  560 
Hexahydro-carvacrol,  459 
Hexahydro-cinchonine,  561 
Hexahydro-cymene,  465,  478 
Hexahydro-durene  hydrogenated,  569 
Hexahydro-guaiacol,  589 
Hexahydro-indoline,  485 
Hexahydro-naphthalid,  563 
Hexahydro-phenanthrene,  484 

dehydrogenated,  642 
Hexahydro-phenylacetic  acid,  476 
Hexahydro-phthalic  acid,  563,  590 
Hexahydro-phthalid,  563 
Hexahydro-phthalimide,  569 
Hexahydro-terephthalic  acid,  648 
Hexahydro-toluene,  581 
Hexahydro-toluic  acids,  471,  563 
Hexahydroxy-anthraquinone,  274 
Hexahydroxy-benzene  hydrogenated,  578 
Hexa-isobutanal  formed,  224 
Hexamethyl-benzene  decom.,  887 

formed,  212,  691 

Hexamethylene  hydrocarbons  dehydro- 
genated, 649 

hydrogenated,  475 
Hexamethylene-tetramine  cond.,  792 

hydrogenated,  496 
Hexane  from  acetylene,  211 

by  cracking,  936 

decom.,  920 

formed,  664,  665 

by  hydrogenation,  414 

as  solvent,  38 

Hexaphenyl-cyclohexane,  880,  916 
Hexene  hydrated,  306 

hydrogenated,  414,  515 


SUBJECT  INDEX 


385 


Hexites,  595 

Hexose  from  HCHO,  221 

Hexyl  alcohol,  801 

Hexyl-benzene  hydrogenated,  569 

Hexyl  cyanide,  814 

High  pressure  in  catalysis,  541 

History  of  catalysis,  4 

Hofmann's  reaction,  901 

Hog  lard,  938 

Homogeneous  catalysis,  5,  144 

Hydration,  305-312,  305-339 

of  acetylene  comps.,  308 

of  ethylene  comps.,  306,  307 

in  gas  phase,  337-339 

of  imides,  311 

in  liquid  medium,  313-331 

mechanism  of,  308 

of  nitriles,  311 

Hydrazine  compounds  decom.,  611 
Hydrazobenzene,  202,  531,  554 
Hydrazo  compounds  hydrogenated,  600 
Hydrazones  decom.,  611 
Hydrindene,  hydrogenated,  454 
Hydrindone  cond.,  799 
Hydro-aromatic  hydrocarbons,  424,  444 

dehydrogenated,  640-649 
Hydrobenzamide,  194 
Hydrobromic  acid  elim.,  901 
Hydrocarbons  from  acetylene,  925 

from  acids,  829-836,  839 

from  alcohol  +  aldehyde,  784 

condensed,  241,  905-936 

decom.,  87,  493,  905-936 

decom.  in  H2,  924 

dehydrogenated,  639-649 

hydrogenated,  413,  444-454,  472  et 
seq.  481^85,  493,  500-502,  506, 
515-518,  526,  527,  534,  565,  566, 
569,  570,  577,  601 

formed,  695-727,  784-815,  829-836, 
839,  925 

oxidised,  254,  259 

polym.,84 
Hydrocarvols,  476 
Hydrochloric  acid  cat.  acetals,  782 

cond.  agt.,  730,  782,  792,  799,  803-805 

dehydration  cat.,  687,  795 

in  esterif.,  748-750,  754-757 

in  hydration,  307 

toxic  to  cats.,  116 
Hydrocinnamic  esters  hydrogenated,  471 


Hydrocyanic   acid   hydrogenated,   342, 

528 

by  hydrolysis,  329 
polym.,  230 
stabilized,  11 
toxic  to  cats.,  116 
Hydrocyclic  hydrocarb.  dec.,  921 
Hydrogen  abs.  by  Co,  136,  by  Pd  165,  by 

Pt  136 

elim.  from  hydrocarb.,  905 
generator,  346 
for  hydrogenation,  953 
influence  in  dec.  hydroc.,  924 
from  iron,  954 
manufacture,  953,  954 
occluded  by  Co,  136,  by  Pd  165,  by 

Pt  136,  166 
purification  of,  346 
rate  of  production  from  Fe,  954 
from  water  gas,  953 
Hydrogenation,  15,  65,  111,  115,  121, 

138,   165,  342-407,  408-497,  498- 

540,  541-583,  563n,  584-604,  721, 

923,  931,  932,  937-969 
of  acetylene,  501,  506 
of  acetylene  comps.,  423  et  seq.,  518, 

527,  566,  577 
of  acid  chlorides,  575 
of  acids,  422,  471 
of  acridine,  491 
by  alcohol  vapors,  537,  538 
of  alcohols,  369,  416,  465 
of  aldehydes,  388,  419,  432,  433,  503, 

522,  532,  567,  588,  602 
of  aliphatic  aldehydes,  432,  532 
of  aliphatic  amides,  386 
of  aliphatic  ketones,  532 
of  aliphatic  nitriles,  427 
of  aliphatic  nitro  comps.,  377 
of  alkaloids,  555 
of  amides,  386 
of  amines,  466,  496 
of  anhydrides,  392 
of  anthracene  nucleus,  483 
apparatus,  345-357,  543,  584-585,  597 

et  seq.,  957-964 
of  aromatic  acids,  471 
of  aromat.  ales.,  369,  465 
of  aromat.  aids.,  388,  433 
of  aromat.  amines,  466 
of  aromat.  diketones,  391 


386 


SUBJECT  INDEX 


of  aromat.  halogen  comps.,  403 

of  aromat.  hydrocarb.  466  et  seq.,  502 

of  aromat.  ketones,  389,  455 

of  aromat.  nitriles,  428 

of  aromat.  nitro  comps.,  378 

of  aromat.  nucleus,  444  et  seq.,  534, 

569,  589 
of  benzene  and  homologs,  466  et  seq., 

502 

of  carbazol,  490 
of  carbon  525 

of  carbonates  to  formates,  574 
of  carbon  dioxide,  395,  504,  508 
of  carbon  disulphide,  372,  492 
of  carbon  monoxide,  393 
by  carbon  monoxide  and  hydrogen, 

537 

by  cobalt,  499-504 
by  colloidal  Pd,  545-555 
by  colloidal  Pt,  556 
of  complex  rings,  571 
by  copper,  507,  523,  594 
of  cyclic  comps.,  578 
with  dehydration,  721,  722 
of  diazo  comps.,  497 
of  dicyanides,  429 
of  diketones,  438 
of  esters,  417 
of  ethers,  418,  494 
of  ethyl  acetoacetate,  387 
of  ethylene  comps.,  500,  506,  515,  526, 

565,  577,  601 

of  ethylene  hydrocarb.,  500,  506,  515 
of  ethylene  oxides,  443 
by  formic  acid,  537,  539 
of  furfuryl  alcohol,  371 
furnace  for,  347,  348 
in  gas  system,  366-407 
of  halogen  comps.,  403  et  seq. 
of  heptamethylene  ring,  479 
of  hexamethylene  ring,  475 
history  of,  342-344,  542,  939 
of  hydrocarbons,  413,  493,  499  et  seq. 
hydrocyanic  acid,  528 
of  indol,  497 
by  iron,  505,  506,  593 
of  isocyanides,  431 
of  keto-acids,  437 
of  ketones,  389  et  seq.,  420,  435  et  seq. 

441,  455,  503,  522,  532,  567,  588, 

602 


of  liquid  fats,  937-969 

in  liquids,  350-352,  541  et  seq.,  584  et 
seq.,  596-603  % 

in  manuf .  of  ill.  gas,  397  et  seq. 

methods,  343  et  seq.,  544,  562, 573,  584, 
596,  597,  599,  604 

of  naphthalene  nucleus,  481,  931 

by  nascent  hydrogen,  537 

of  nitriles,  427,  428,  521 

of  nitro  comps.,  377,  378,  509,  529, 
564,  576,  600 

of  nitrous  esters,  513 

of  nitrous  oxide,  368 

of  octomethylene  ring,  480 

of  oxides  of  carbon,  504 

by  oxides  of  metals,  598,  943 

of  oxides  of  N,  374 

of  oximes,  283,  514 

by  palladium,  536,  544-555,  573-578 

by  palladium  black,  573-578 

of  pentamethylene  ring,  474 

of  phenanthrene  nucleus,  484 

of  phenol  ethers,  464,  494 

of  phenols,  370,  456 

of  phenyl  isocyanate,  495 

by  platinum,  524-535,  550-571 

by  platinum  black,  562-572 

of  polycyclic  hydrocarbons,  452 

of  polymethylene  rings,  535 

of  polyphenols,  370,  460 

products,  355,  356,  965 

of  pyridine,  486 

of  pyromucic  aid.,  434 

of  pyrrol,  486 

of  quinoline,  488 

of  quinones,  442 

removes  odors,  939 

results  of,  355,  356,  965 

of  solids,  353 

temperatures  for,  599 

of  terpenes,  477,  570,  591 

of  tetramethylene  ring,  473 

theory  of,  167,  365 

of  trimethylene  ring,  472 

by  various  metals,  580,  595 

of  various  rings,  472  et  seq.,  571,  592, 

603 

Hydrogen  halides  elim.,  875-903 
Hydrogen  ions  in  hydrol,  82,  313,  324 
Hydrogen  peroxide  decom.,  2,  32,  38,  83, 
160,  180a 


SUBJECT  INDEX 


387 


with  chromic  acid,  147 

oxidising  agt.,  268 

with  permanganate,  148 

stabilized,  11,  13 
Hydrogen  persulphides,  83 
Hydrogen  selenide  decom.,  8 
Hydrogen  sulphide,  686,  743,  791,  810, 
924,  947 

with  alcohols,  743 

with  aldehydes,  810 

elim.,  626-629 

isom.  agt.,  182 

toxic  to  cats.,  1800,  598,  947 
Hydroiodic  acid  cat.,  82,  183 

decom.  limit,  15,  20 

formation,  342 

isom.  cat.,  182 
Hydrolecithin,  555 
Hydrolysis,  82,  175-178,  305,  313-336 

of  acetals,  322 

by  acids,  313 

of  amides,  331 

by  bases,  318 

of  carbon  disulphide,  339 

of  esters,  313-319,  337 

of  ethers,  321,  338 

in  gas  system,  337-339 

of  glucosides,  327 

of  halogen  comps.,  320 

of  polysaccharides,  323 
Hydropivalic  acid  esterif.,  227 
Hydroquinine,  604 
Hydroquinone  by  hydrogenation,  442 

reduced,  370,  461,  589 
Hydroxy-acids  esterif.,  756 
Hydroxy-anthraquinones  by  oxidation, 

274 
Hydroxy-benzoic     acid     hydrogenated, 

569 

Hydroxy-butyric  aldehyde  formed,  307 
Hydroxy-cyclohexanes  dehydrated,  642 
Hydroxy-esters  dehydrogenated,  663 
Hydroxy-isoheptoic  acid,  663 
Hydroxylamine  by  hydrol.,  332 
Hydroxyl  group  elim.,  465 

introduced,  269 
Hydroxy-methylene   comps.    hydrogen- 

ated,  550 
Hydroxy-stearic  acid  formed,  306 

toxic  to  cats.,  115 
Hypochlorites  as  oxidising  agents,  270 


Hypogaelc  acid,  184 
esters  of,  937 

Illuminating  gas  by  hydrogenation,  397- 
402 

freed  from  CS2,  372 

manufacture,  397-402 

purification,  339,  372 
Imbibition  of  liquids  by  porous  sub.,  133 
Imides,  305,  312 
Indene  polym.,  217 
Indose,  186 

Indigo  hydrogenated,  165,  603 
Indigotine  hydrogenated,  603 
Indigo  white,  165,  603 
Indol,  684 

hydrogenated,  497,  571 
Indols  cond.,  803 

formed,  89,  91,  633 
Induced  catalysis,  149 

oxidations,  244 
Influence  of  solvents,  38-40 
Infra-red  radiation  as  cat.,  180j 
Infusorial  earth  as  carrier,  126,   587n, 

598,  941 
Inosite,  578 

Intermediate  comps.  in  cat.,  151-158, 
163-173,  179,  180,  752,  763,  859- 
864,  866,  872,  878,  898,  916 

in  esterif.,  752,  763 

in  F.  and  C.  syn.,  898 

in  oxidation,  258,  541,  677 
Inversion  of  reactions,  14 

of  sugar,  32,  324 
Iodides  cats.,  84 
lodination,  294 
Iodine  absorbed,  938 

bromination  cat.,  291 

catalyst,  6,  33,  43,  156,  278,  299,  632 

chlorination  cat.,  156,  278n,  287 
Iodine 

dehydration  cat.,  699,  729,  790 

elim.,  406,  605 

isom.  cat.,  182 

sulphonation  cat.,  296,  815,  815n 

toxic  to  cats.,  116,  359 
Iodine  numbers,  938,  955 

of  hardened  oils,  967,  967n 

in  hydrogenation,  966 
Iodine  trichloride  catalyst,  44,  85,  156 

chlorination  cat.,  85,  278 


388 


SUBJECT  INDEX 


lodobenzene  reduced,  406 

in  syn.,  904 
lonones  formed,  198 

hydrogenated,  554,  560 
Ions  in  hydrolysis,  305 
Indium  black,  582 

catalyst,  64 

colloidal  oxid.  cat.,  251 
Iron,  bromination  cat.,  293 

catalyst,    167,    180r-180w,   320,   344, 
505,  506,  540,  683 

catalyst,  prep,  of,  58 

chlorination  cat.,  278n,  285,  285n 

cracking  cat.,  906,  910,  911,  932 

dec.  C2H2,  913,  915,  920,  928 

dec.  alcohols,  667 

dec.  aromat.  hydrocarb.,  921 

dec.  CO,  615 

dec.  ethylene,  912 

dec.  pinene,  922 

dehydrogenation  cat.,  637,  651,  652, 
667 

in  drying  oils,  266 

harmful  in  hydrogenation,  115 

hydrogenation  cat.,  344,  505,  506,  593, 
945 

in  hydrolysis  of  benzalchloride,  320 

influence  on  Pd,  946 

method  for  prep,  of  hydrogen,  953, 

954 

Iron  benzoate,  320 
Iron  borate  cat.,  265 
Iron  bromide,  bromination  cat.,  240,  293 
Iron  chloride,  bromination  cat.,  293 

chlorination  cat.,  283 

cracking  cat.,  936 

in  F.  and  C.  syn.,  88 

halogenation  cat.,  88 

hydration  cat.,  310 

polym.  cat.,  216 

prep,  acetals,  88 
Iron  compounds  cats.,  269n 
Iron  hydroxide  oxid.  cat.,  150 
Iron  oxides  cat.,  6,  75, 100,  260,  285,  310, 
320 

dehydration  cat.,  702 

hydration  cat.,  310 

ketone  cat.,  843,  849 

oxidation  cat.,  257-259 

prep.,  77 
Iron  powder  cat.,  320 


Iron  retorts  in  cracking,  934 

Iron  salts  oxid.  cat.,  268,  271,  277,  320 

reduced,  Pd  165 
Iron  scale  cat.,  285 

Iron  sesquioxide  chlorination  cat.,  285 
Iron  sulphate  chlorination  cat.,  285 

oxidation  cat.,  272,  275 
Iron  sulphide  chlorination  cat.,  284 
Isoamyl  acetate  dec.,  871 
Isoamyl  alcohol  into  amines,  733,  740, 
741 

dehydrated,  691,  696,  713,  715,  717, 
719 

dehydrogenated,  656,  664,  672 

esterified,  771,  773 

oxidised,  254,  268 
Isoamyl  amine  from  alcohol,  733 

catalyst,  836 

dehydrogenated,  681 

by  hydrogenation,  382 
Isoamyl  benzoate,  766 
Isoamyl-carbinol  hydrogenated,  570 
Isoamyl  cyanide  hydrogenated,  427 
Isoamyl  ether,  691 
Isoamyl  formate,  773 
Isoamyl  hexahydrobenzoate,  471 
Isoamyl  malonate  dec.,  873 
Isoamyl  mercaptan,  626,  744,  746 
Isoamyl  nitrite  hydrogenated,  382 
Isoamyl  oxalate  dec.,  873 
Isoamyl-phenyl  ether,  789 
Isoamyl-piperidine,  741 
Isoamyl  succinate  dec.,  873 
Isoamyl  sulphide,  626 
Isobutane,  472 

Isobutyl  acetate  dec.,  861,  862 
Isobutyl  alcohol  into  acetal,  780 

from  aldehyde,  226 

dehydrated,  691,  696,  700,  713,  715- 
717 

dehydrogenated,  656,  670 

esterified,  771,  776 

oxidised,  249,  254,  268 
Isobutyl-amine  by  hydrogenation,  382 
Isobutyl  benzoate,  766 
Isobutyl  bromide  isom.,  200 
Isobutyl  chloride  dec.,  878,  881 

in  F.  and  C.  syn.,  900 
Isobutyl  cyanide,  681,  682 
Isobutylene  formed,  142,  713,  878 

hydrated,  306 


SUBJECT  INDEX 


389 


Isobutyl  ether,  691 
Isobutyl  hexahydrobenzoate,  471 
Isobutyl-isoamyl-amine,  738 
Isobutyl  isobutyrate  from  aid.,  226 
Isobutyl  malonate  dec.,  873 
Isobutyl  mercaptan,  744 
Isobutyl  nitrite  hydrogenated,  382 
Isobutyl  oxalate  dec.,  873 
Isobutyl  succinate  dec.,  873 
Isobutyric  acid  from  aid.,  226 

dec.,  839 

esterif.,  770,  771,  775,  776 

into  ketone,  840,  842-845 
Isobutyric  aldehyde  from  ale.,  670 

cond.,  808 

crotonized,  795 

into  ester,  226 

hydrogenated,  432,  588,  593 

by  oxidation,  249 

phenylhydrazone  dec.,  635 

polymerized,  224 
Isobutyryl  chloride,  813 
Isocamphane,  591,  722 
Isocrotonic  acid  hydrogenated,  Pd  546 
Isocyanates  from  diazo,  610 

hydrogenated,  431 
Isocyanides  hydrogenated,  431 
Isocyanic  esters  hydrol.,  334 
Isodulcite  by  hydrol.,  328 
Isoeugenol  formed,  191 

hydrogenated,  Ni  590 

oxidised,  249 
Isoheptoic  aldehyde,  635 
Isomerizations,  181-208 
of  alkyl  halides,  876 

in  F.  and  C.  syn.,  888 
Iso-oleic  acid  hydrated,  306 
Iso-oximes  formed,  205 
Isopentane,  681 

by  hydrogenation,  414,  420,  472 
Isopentene  isom.,  190 
Isoprene  formed,  235,  723,  802,  909 

polym.,  50,  106,  213,  214 
Isopropyl-acetylene,  192 
Isopropyl  alcohol,  439,  503,  567,  588, 
593,  594,  784 

into  amine,  735 

dec.  by  C,  679 

dehydrated,  700,  716,  719 

dehydrogenated,  659,  665,  668 

esterif.,  757,  766,  775 


from  gases,  306n 

by  hydrogenation,  391 

oxidised,  254n 

preparation,  435 
Isopropyl  amine  from  ale.,  735 

by  hydrogenation,  382 
Isbpropyl-benzene  hydrogenated,  448 
Isopropyl  benzoate  dec.,  871 

formed,  766 

Isopropyl  bromide  by  isom.,  93,  199 
Isopropyl  chloride  by  isom.,  199 
Isopropyl-cyclohexane,  449,  452 
Isopropyl-cyclohexyl-amine,  739 
Isopropyl-cyclopentanone,  546 
Isopropyl-ethylene,  713 
Isopropyl-guaiacol,  565 
Isopropyl  iodide,  605 
Isopropyl  nitrite  hydrog.,  382 
Isopropylidene-cy clopentanone  hydrog. , 

546 
Isosafrol  hydrogenated,  418,  565,  590, 

601 

Isosulphocyanic  esters  hydrol.,  334 
Isothujone  formed,  198 

hydrogenated,  552 
Isovaleraldoxime,  814 
Isovaleric  acid  into  aid.,  853 

dec.,  839 

esterif.,  771 

into  ketone,  842-844 
Isovaleric  aldehyde  cond.,  808 

formed,  664 

hydrogenated,  432,  588 

by  oxidation,  268 

phenylhydrazone  dec.,  635 
Isovaleric  anhydride  into  ketone,  857 
Isovaleric  esters  dec.,  871 
Isovalerone,  420 
Isovaleronitrile,  814 
Isovaleryl  chloride,  813 
Isozingiberene  hydrogenated,  570 
Itaconic  acid  formed,  183 

hydrogenated,  558 

isom.,  183 

Jena  glass  cat.,  827 

Kaolin  carrier  for  Ni,  941 
dehydration  cat.,  99,  717,  723,  726, 

802 
oxidation  cat.,  267 


390 


SUBJECT  INDEX 


Kayser's  apparatus,  963 
Ketimines  formed,  809 
Keto-acids  esterif.,  756 

hydrogenated,  437 

syn.  of,  902 

Keto-alcohols  dehydrogenated,  663 
Keto-esters,  663 

Keto-hydrofurfuranes  formed,  195 
Keto-isoheptoic  esters,  663 
Ketones  from  alcohols,  650,  659 

into  alcohols,  549 

alicyclic  hydrogenated,  436 

aliphatic  hydrogenated,  435 

aromatic  hydrogenated,  441,  455 

condensed,  81,  238,  794-801,  803-810 

condensed  in  gas  phase,  801 

crotonized,  794-800 

crotonized  in  gas  phase,  801 

decom.,  Ni  620,  Ft  532 

dehydrated,  794-800,  802 

from  esters,  860,  861 

formed,  31,  75,  208,  332,  701,  723,  764, 
829,  830,  837-851,  857,  858,  865, 
891-894 

formed  in  liq.  phase,  847 

by  hydration,  305,  308 

hydrogenated,  420,  435,  436,  441,  455, 
Co  503,  Cu  522,  Fe  506, 593,  Ni  588, 
602,  Pd  549,  Ft  532,  567,  568 

from  oximes,  332 

polym.,  229 

from  second,  ales.,  659 

syn.  by  F.  and  C.,  891-894 
Ketoximes  dehydrated,  814 

hydrogenated,  383,  385,  514 
Kieselguhr,  carrier,  942 
Kream  Krisp,  967n 

Lactones  by  hydrogenation,  392 

Lactose,  323 

Laevulinic  acid  esterif.,  756 

hydrogenated,  437 
Laevulose  formed,  221,  236,  237 

hydrogenated,  Ni  588,  Pd  595 

multirotation,  188 
Lampblack  cat.,  811 
Lard,  938 

Lard  oil  hardened,  966 
Laurie  acid  into  ketone,  843,  850 
Lead  in  drying  oils,  266 

influence  on,  Pd  946 


toxic  to  cats.,  115 
Lead  chamber  process,  32,  158 
Lead  chloride  cat.,  876, 

not  cat.  283 

Lead  hydroxide,  isom.  cat.,  186 
Lead  nitrate,  oxidation  cat.,  277 

reduced  with  Pt,  166 
Lead  oxide  cat.,  676 
Lead  soaps  toxic  to  cats.,  115 
Life  of  catalysts,  111,  708,  947 
Ligroine  as  solvent  in  F.  and  C.  syn., 

892,  897 
Lime  catalyst,  540,  827 

decom.  methane,  911 

dehydration  cat.,  795,  797 

ketone  cat.,  840,  849 
Limits  of  esterification,  750,  751,  767- 
770 

change  with  temperature,  768-770 
Limits  of  reactions,  22,  313 
Limonene  dehydrogenated,  644 

formed,  198 

hydrogenated,  Cu  517,  Ni  477,  591, 

Pt570 
Linalool    hydrogenated,    Ni   416,    601, 

Pt565 
Linoleic  acid  constituent  of  fats,  937 

hydrogen  req.  for  sat.,  955 

hydrogenated,  Pd  558 
Linoleic  esters,  937 
Linolenic  esters,  937 
Linseed  oil  alcoholized,  341 

hardened,  966 

iodine  number,  938 
Liquid  fats  hydrogenated,  937-969 
Lithium  carbonate  ketone  cat.,  846 
Lyxonic  acid,  187 

Magnesia  carrier,  127 

catalyst,  540,  702,  828,  901,  906,  920 
Magnesium  carrier,  Pd  946 

cat.,  51,  901 

in  cracking,  906 

dec.  C2H2,  920 

powder  cat.,  901 

Magnesium  compounds  cats.,  269n 
Magnesium  sulphate  dehydration  cat., 

101 
Maleic  acid  cat.,  196 

hydrogenated,  558 

isomer.,  182 


SUBJECT  INDEX 


391 


by  oxidation,  260n,  276 

oxidised,  268 

toxic  to  cats.,  115 
Malic  acid  esterif.,  756 
Malichite  green  hydrogenated,  603 
Malonic  acid  cond.,  804 
Malonic  anhydride,  873 
Malonic  ester  cond.  aids.,  804 
decom.,  873 

Malonyl  chloride  in  F.  and  C.  syn.,  893 
Maltose  hydrol.,  323,  325 
Manganese  bromination   cat.,   52,   292 

in  drying  oils,  266 

oxidation  cat.,  52,  254 
Manganese  chloride  cat.,  283 
Manganese  dioxide  cat.  H2O2,  75 
Manganese  oxides  oxidation  cat.,  259 
Manganese  salts  cats.,    100,   153,  264, 

269n 

Manganous  acetate,  268 
Manganous  borate,  265 
Manganous  oxide  cat.,  259,  617,  702, 
828,  840,  845,  850,  853,  866 

on  alcohols,  142 

dehydrogenation  cat.,  651,  672 

ketone  cat.,  840,  845,  850 
Manganous  salts  oxidation  cats.,   100, 

153,  264,  268 
Mannite  esterif.,  757,  761 

by  hydrogenation,  588,  595 

oxidised,  150 
Mannite  hexacetate,  761 
Mannonic  acid  formed,  187 
Mannose  isom.,  186 

by  oxidation,  150 
Margaric  esters,  937 
Mechanical  shaking,  562 
Mechanism  of  amine  formation,  731 

of  hydrogenation,  677 

of  Grignard  reaction,  300,  301 

of  hydration,  308 

of  mercaptan  decomp.,  627 

of  oxidation,  258,  264,  276 

of  poisoning,  180p-180s 

of  promoters,  180s-180u 
Melissic  acid  into  ketone,  843 
Melting  points  of  hardened  oils,  966, 

967n 
Menthane,  369,  449,  465,  475,  477,  478, 

518,  570,  591,  722 
Menthane-diol,  463 


Menthene  by  dehydration,  714 

dehydrogenated,  644 

hydrogenated,  475 
Menthol,  436,  567 
Menthone  hydrogenated,  Pt  567 

by  hydrogenation,  552,  591 

isom.,  189 

Menthone-oxime  hydrogenated,  385 
Mercaptans  formed,  75,  170,  626-628, 

707n,  743-746 
Mercaptans,  secondary,  628 
Mercaptides,  627 
Mercuric  bromide  bromination  cat.,  293 

hydration  cat.,  309 

Mercuric  chloride  with  Al  on  alcohols, 
299 

with  Al  in  F.  and  C.  syn.,  886 

bromination  cat.,  293 

hydration  cat.,  92,  309 

isom.  cat.,  92 

toxic  to  cats.,  116 
Mercuric  nitrate  nitration  cat.,  269n 

oxidation  cat.,  269 
Mercuric  salts  red.  with  Pd,  165 
Mercuric  sulphate  hydration  cat.,  102, 
309 

oxidation  cat.,  272-274 

sulphonation  cat.,  6.,  102,  816 
Mercury  dec.  H2O2,  180a 
Mercury  oxide  oxidation  cat.,  269n 
Mesaconic  acid  formed,  183 
Mesitylene  with  CO,  298 

hydrogenated,  447 

by  isom.,  888 

by  polymer.,  212 
Mesityl  oxide,  697,  699,  797,  801 

hydrogenated,  420,  549,  Ni  587,  Pd 

546,  595,  Pt  559,  567 
Meso-benzo-dianthrone        dehydrogen- 
ated, 685 

Meso-naphtho-dianthrone,  685 
Meta-aldehydes  depolym.,  234 

formed,  222 

Meta-butanal  formed,  223 
Meta-chloral  formed,  224 
Meta-heptaldehyde  formed,  223 
Meta-isobutanal  formed,  224 
Metal  chlorides  as  cats.,  876 
Metal  oxides  as  cats.,  169,  675,  881 

dehydration  cats.,  686 
Metals,  compounds  formed,  299,  300 


392 


SUBJECT  INDEX 


cond.  of  gases  on,  135 

in  cracking,  906,  932 

decom.  acetylene  hydrocarb.,  913-919 

dec.  aromat.  hydrocarb.,  921 

dec.  esters.,  867 

dec.  formic  acid,  823 

dec.  formic  esters,  867 

dehydration  cats.,  686,  687,  701 

ketone  cats.,  830,  847 
Meta-propional  formed,  223 
Meta-styrene,  657 

Methane,  432,  495,  504,  536,  540,  593, 
620,  631,  634,  641,  645,  664,  672 

from  CO2  by  hydrogenation,  395-402 

from  CO,  393 

decom.,  Mg  920,  Ni  911 

equilib.  in  formation,  409-411 

formed,  362,  369,  370,  377,  393,  395- 
402,  409-411,  413,  525 

formed  from  carbon,  586 

by  hydrogenation,  362,  369,  370,  377, 
395-402 

oxidised,  253 

Methods  of  hydrogenation,  599  ei  seq. 
Methoxy-cyclohexane,  464,  494 
Methoxy-methyl-cyclohexanols,  464 
Methoxy-propylbenzene,  590,  601 
Methoxy-propyl-cyclohexane,  590 
Methoxy-propyl-phenol,  590 
Methyl  acetate  dec.,  180j 

hydrol.,  313 

Methyl-acetyl-acetone  hydrogenated,  439 
Methylal  cond.  with  phenols,  792 

formed,  781 

by  oxidation,  249 

Methyl  alcohol,  432,  538,  740,  771,  773, 
851 

into  acetal,  781 

dehydrated,  688,  690,  691,  693,  713, 
715,  716 

dehydrogenated,  656,  676,  CdO  674, 
MnO  672,  Ni  664,  SnO  673,  Zn  678 

detection  in  EtOH,  656 

esterif.,  771,  773 

from  formic  acid,  826 

oxidised,  249,  268 

with  phenol,  789 

with  Pt,  668 
Methyl-allene,  784 

Methyl-amine  from  HCN  by  hydrogena- 
tion 342,  528 


by  hydrogenation,  377,  382,  510,  530 

oxidised,  256 

Methyl-amyl-acetylene,  308 
Methyl-aniline  dec.,  634 

formed,  729,  740 

hydrogenated,  468 

Methyl-anthracene  from  cracking,  909 
Methyl-anthraquinone  nitrated,  269n 
Methyl  benzoate  alcoholized,  340n 

dec.,  871 

by  esterif.,  744n,  766 

hydrogenated,  471 

into  nitrile,  871 
Methyl-butadiene,  802 
Methyl-butane-diol  dehydrated,  723 
Methyl-tert-butyl-amine,  430 
Methyl-butyl  ketone  hydrogenated,  435 
Methyl-butyl-phenol,  459 
Methyl-carbyl-amine  hydrogenated,  430 
Methyl-carvacryl  ether,  789 
Methyl-chlorcyclohexane,  569 
Methyl  chloride  in  F.  and  C.  syn.,  884 
Methyl  cinnamate  hydrogenated,  601 
Methyl-p.cresyl    ketone    hydrogenated, 

389 

Methyl-cyclohexane,  197,  447-450,  452, 
465,  467,  479,  560,  590,  641 

dehydrogenated,  641 

by  hydrogenation,  388 

by  isom.,  197 

Methyl-cyclohexyl-amine,  739 
Methyl-cyclohexanols  into  amines,  739 

dehydrogenated,  660 

by  hydrogenation,  457 
Methyl-cyclohexanones  by  dehydrogena- 
tion,  660 

hydrogenated,  436,  567 
Methyl-cyclohexanone-hydrazones,  611 
Methyl-cyclohexenes,  515,  660 
Methyl-cyclohexyl-amine,  467,  737,  739 
Methyl-cyclohexyl-aniline,  467 
Methyl-cyclopentane  by  hydrogenation, 

390,  649 

Methyl  cyclopentane-carbonate,  649 
Methyl-cyclopentanone     hydrogenated, 

390,  436 

Methyl-cyclopropene  hydrogenated,  472 
Methyl-diphenyl  carbinol,  721 
Methylene  chloride  in  F.  and  C.  syn., 

896 
Methylene-dithiol,  492 


SUBJECT  INDEX 


393 


Methyl  esters  by  alcoholysis,  341 

dec.,  860,  865,  871 
Methyl  ether,  688,  690,  691,  693,  713, 

865,  871 

Methyl-ethyl-acetylene,  192 
Methyl-ethyl-acroleine      hydrogenated, 

595 

Methyl-ethyl-amine,  430 
Methyl-ethyl-benzene  by  hydrogenation, 

389 

from  pinene,  922 

Methyl-ethyl-butadiene  formed.  192 
Methyl-ethyl  carbinol,  567 
Methyl-ethyl-cyclohexane,  448,  449 
Methyl-ethyl-cyclohexene  hydrogenated, 

475 

Methyl-ethyl  ether,  691 
Methyl-ethyl-ethylene  formed,  193 
Methyl-ethyl  ketone  hydrogenated,  567 
Methyl-ethyl   ketone   phenylhydrazone 

dec.,  633 
Methyl-ethyl-propenal        hydrogenated 

546,  559 

Methyl-di-isopropyl-benzene,  930 
Methyl  formate  from  aid.,  228 
dec.,  868 
by  esterif.,  773 
Methyl-furfurane  hydrogenated,  487 

by  hydrogenation,  371 
Methyl-heptanone    by    hydrogenation, 

420 
Methyl-heptenone    hydrogenated,    420, 

552 

Methyl  hexahydrobenzoate,  471 
Methyl  hexahydroterephthalate,  648 
Methyl-hexanone,  420 
Methyl-hexenone  hydrogenated,  420 
Methyl-hexyl  carbinol  dehydrogenated, 

665 

Methyl-hexyl  ketone,  665 
Methyl-indol,  489,  633,  684 
Methyl-isobutyl-benzene  by  F.  and  C. 

syn.,  900 

Methyl-isobutyl  carbinol,  549,  559,  568 
Methyl-isobutyl  ketone,  435,  545,  559, 

567,  587,  595 

Methyl-isopropyl-cyclohexane,  449,  475 
Methyl-isopropyl    ketone    dehydrated, 

802 

hydrogenated,  435 
Methyl  mercaptan,  744 


Methyl-naphthyl  ketone  hydrogenated, 

390 

Methyl  nitrite  hydrogenated,  382,  513 
Methyl-nonyl  ketone  hydrogenated,  435 
Methyl-pentanol,  559,  595 
Methyl-pentanone,  420 
Methyl-pentamethylene,  444 
Methyl-pentene  hydrated,  306 
Methyl-pentyl  alcohol,  546 
Methyl-phenyl-butine-ol  hydrogenated, 

548 

Methyl-phenyl  carbinol,  728 
Methyl-propyl  carbinol,  487 
Methyl-propyl-octane  by  hydrogenation, 

166 

Methyl-propyl-octene  hydrogenated,  414 
Methyl-propyl    ketone    hydrogenated, 

435 

by  hydrogenation,  487 
Methyl-quinoline,  488 
Methyl-salicylic  aid.  hydrogenated,  568 
Methyl  tetrahydroterephthalate     dehy- 
drogenated, 648 
Methyl-toluidines,  684,  740 
Methyl-valeric  aid.,  546 
Methyl-vanilline  hydrogenated,  568 
Mexican  petroleum  cracked,  933 
MFB,  967n 

Migration  of  atoms,  199 
Migrations  of  double  and  triple  bonds, 

190 

Mineral  acids  as  cats.,  81 
Mixed  amines,  738 
Mixed  catalysts,  538,  651,  675,  702,  826, 

827,  866 

Mixed  ethers  formed,  170,  789 
Mixed  ketones,  75,  847-850 
Mixed  oxide-catalysts,  538 
Mixed  phenol-ethers,  788,  789 
Moisture  in  oils,  949 
Molybdenum  chloride  chlorination  cat., 

90,  283,  286 

Molybdenum  compounds  cats.,  269n 
Molybdenum  oxide  cat.,  675,  676,  693, 

702,  827 
Molybdenum  oxide,  blue  cat.,  675,  746, 

791 

Molybdenum  promoter,  180s,  180u 
Monobasic  acids  dec.,  829-854 
Morphine  hydrogenated,  572 
oxidised,  268 


394 


SUBJECT  INDEX 


Mucic  acid  dehydrated,  727 

esterif.,  756 

formed,  187 

Multirotation  of  sugars,  188 
Mustard  oils  hydrol.,  333 
Mutton  tallow,  938 
Myrcene  formed,  214 
Myristic  acid  into  ketone,  850 

Naphthalene  cond.,  806 

from  cracking,  908,  909 

dec.,  921,  931 

dec.,  by  A1C13.,  931 

by  dehydrogenation,  642 

formed,  908 

in  F.  and  C.  syn.,  889,  899 

hydrogenated,  481,  Ni  592,  Pd  553, 
Pt571 

by  hydrogenation,  379 

oxidised,  273 
Naphthalene  hydrides  from  C2H$,  914 

dehydrogenated,  642 
Naphthalic  acids  hydrogenated,  594 
Naphthalic     anhydride     hydrogenated, 

563 

Naphthane,  481 
Naphthenes  formed,  211 
Naphthoic  acid  esterif.,  756 
Naphthols  into  amines,  790 

hydrogenated,  481,  592 
Naphthol  ethers  hydrogenated,  494 
Naphthonitriles  formed,  871 
Naphthoyl  chlorides  in  F.  and  C.  syn., 

899 
Naphthyl-amines,  512,  630,  632,  729 

hydrogenated,  496 

by  hydrogenation,  379 
Naphthyl  ethers,  789 
Naphthyl  ketones  by  F.  and  C.  syn.,  899 
Natural  gas,  928 
Negative  catalysts,  9,  11 
Neutral  salt  effect  in  hydrol.,  317,  319 

in  inver.  of  sugar,  324 
Nickel,  a,  0,  and  y  forms,  360 

amount  of  required,  951 

carrier  for,  Pd  946 

on  carrier,  126,  598,  939,  941,  942,  959, 
960 

cat.,  15,  24,  53,  111-115,  122,  167, 
180Z-180n,  343,  344,  358,  539,  540, 
563n,  584  et  seq.,  596-603,  614,  619, 


620,  683,  721,  722 

cat.  preparation,  54-56,  598,  941 

in  cracking,  906,  910,  911 

dec.  C2H2,  913,  918-920,  925,  926 

dec.  alcohols,  1800,  664 

dec.  aldehydes,  619 

dec.  amines,  631,  634 

dec.  aromatic  hydrocarb.,  921 

decomp.  cat.,  832,  834,  867,  910-913, 
918-921,  923,  925,  926 

dec.  CO,  163 

dec.  chlorides,  882 

dec.  esters,  1806,  ISO/,  18Q/ 

dec.  formic  esters,  867 

dec.  hydrocarb.,  832,  834,  867,  910- 
913,  918-921,  923,  925,  926 

dec.  ketones,  620 

dec.  pinene,  923 

dehydrogenation  cat.,  636,  637,  640- 
645,  647,  651,  664,  665,  681,  684, 
701,  824 

elim.  NH3,  631 

in  hardened  oils,  969 

hydrogen  comps.,  167 

hydrogenation  cat.,  197,  801,  932,  939, 
941-945,  947,  948,  950,  951,  969 

hydrogenation  cat.  for  fats,  939,  941- 
948,  950,  951 

isom.  cat.,  208 

from  Ni(CO)4,  163,  598,  616,  942,  953 

preparation  of,  53-56,  598,  941 

on  pumice,  126,  939,  941,  942 

temp,  for  use,  952 
Nickel  acetate,  944 
Nickel  borate  cat.,  265,  944 
Nickel  carbonate,  941 
Nickel  carbonyl,  163,  598,  616,  942,  953 
Nickel  chloride  cat.,  283,  876,  880,  947 
Nickeled  asbestos,  959,  960 
Nickeled  pumice,  126,  939,  941,  942 
Nickel  formate,  944 
Nickel  lactate,  944 
Nickel  nitride,  375 

Nickel  oxide  cat.,  75,  80,  254,  258,  259, 
722,  943 

hydration  cat.,  310 

hydrogenation  cat.,  584,  598 

vs.  nickel,  584 

theory,  258 
Nickel  peroxide,  180a 
Nickel  sesquioxide,  589 


SUBJECT  INDEX 


395 


Nickel  suboxide,  80,  598,  943 
Nickel  sulphate  oxid.  cat.,  272 
Nitranilines  hydrogenated,  Cu  513 
Nitration  catalyzed,  269rc 
Nitric  acid  from  NH3,  150,  249 

in  hydration,  307 

hydrogenated,  376 

on  metals,  8 

oxidising  agent,  269 
Nitric  oxide  hydrogenated,  374,  Cu  509, 

Pt529 
Nitrites,  305,  633,  635,  681,  682,  808 

formed,  15,  631,  811,  812,  814 

hydrated,  311 

hydrogenated,  426-429,  521 

polymerized,  230 

Nitriles,  aliphatic  hydrogenated,  427 
Nitriles,  aromatic  hydrogenated,  428 
Nitroacetophenone  hydrogenated,  545, 

557 

Nitro-alcohols  formed,  236 
Nitrobenzaldehyde  cond.,  798 

by  oxidation,  270 
Nitrobenzene  formed,  819 

hydrogenated,  378,  538,  545,  Cu  511, 
Pd  536,  576,  Pt  531,  537 

oxidising  agent,  277 

solvent  for  F.  and  C.  syn.,  892 
Nitrobenzophenone  F.  and  C.  syn.,  893 
Nitrobenzoyl  chlorides  in  F.  and  C.  syn., 

893 
Nitro  compounds  cond.,  803 

from  diazo,  609 

hydrogenated,  377,  378,  Cu  509,  Fe 
506,  Ni  600,  Pd  545,  576,  Pt  529, 
557,  564 

Nitro  compounds,  aliphatic  hydrogen- 
ated, 377 

Nitro  compounds,  aromatic  hydrogen- 
ated, 378 
Nitro-ethane  cond.,  236 

hydrogenated,  377,  510 
Nitrogen  eliminated,  606-612 
Nitrogen  dioxide  hydrogenated,  529 
Nitrogen  oxides  hydrogenated,  529 
Nitrogen  peroxide  hydrogenated,  375, 

509 
Nitromethane  cond.,  236,  803 

hydrogenated,  377,  Cu  510,  Pd  536, 

Pt530 
Nitro-methanol-butanol,  236 


Nitro-methylol-propane-diol,  236 
Nitronaphthalene    hydrogenated,    379, 

512 

Nitroparaffines  cond.,  236 
Nitrophenols  hydrogenated,  381,  Cu  512, 
Pd536 

by  oxidation,  269 
Nitrophenyl-ethylene,  803 
Nitropropane  cond.,  236 
Nitropropanol,  236 
Nitropropyl  alcohol,  236 
Nitrosamines,  108 
Nitroso  compounds  as  cats.,  108 

hydrogenated,  564 

Nitroso-dimethyl-aniline  in  vulc.,  104 
Nitroso-naphthol  hydrogenated,  564 
Nitroso-phenol  as  cat.,  108 
Nitroso-terpenes  hydrogenated,  564 
Nitrostyrene  hydrogenated,  565 
Nitrotoluenes    hydrogenated,   378,    Cu 
512,  Pt  564 

by  hydrogenation,  378 
Nitrous  acid  cat.,  82,  184,  269n 

esters  of  hydrogenated,  382,  509,  513 
Nitrous  oxide  hydrogenated,  368,  509 
Nonane  by  hydrogenation,  414 
Nonene  hydrogenated,  414 
Nonylic  acid  into  aid.,  852,  853 

into  ketone,  845 
Nonylic  aldehyde,  852-854 
Nonylic  esters  dec.,  871 

Occlusion  of  gases,  180 

Ocimene  hydrogenated,  415 

Octadiene-diol  hydrogenated,  566 

Octadiene-diolic  acid  hydrogenated,  566 

Octane  by  hydrogenation,  414,  601 

Octane-diol,  566 

Octene  hydrogenated,  414,  Cu  515,  Ni 

601 

Octodecyl  alcohol,  565 
Octohydro-anthracene,  29,  363,  390,  483 
Octohydro-indol,  571 
Octohydro-phenanthrene,      484,      536, 

592 

Octoic  acid  into  aid.,  853 
Octoic  aid.,  853 

Octomethylene  ring  hydrogenated,  480 
Octo-trienal,  801 
Octyl  alcohol,  566 
Octyl-benzene  hydrogenated,  569 


396 


SUBJECT  INDEX 


Odors  of  oils  elim.  by  hydrogenation, 

939,  965 

Oenanthaldoxime,  814 
Oenanthylidene  hydrogenated,  425 
Oenanthylidene-acetic    acid    hydrogen- 
ated, 417 

Oils  hydrogenated  in  vapor,  939 
Oils  oxidised,  265 
Oklahoma  petroleum  cracked,  935 
Oleic  acid,  amt.  H2  required,  955 

in  fats,  937 

hydrogenated,  422,  562,  939,  955, 
Cu  515,  Ni  587,  601,  Pd  546,  577, 
Pt  558,  565 

isom.,  82,  184 

into  ketone,  843 
Oleic  esters  in  fats,  937 

hydrogenated,  577,  601 
Oleic  alcohol  hydrogenated,  565 
Oleine,  937,  939,  955 

amt.  H2  required,  955 

into  stearine,  939 
Olive  oil  hardened,  966 

iodine  number,  938 
Optical  isomers,  186 
Organic  Mg  compounds,  300-302 
Origin  of  petroleum,  925-928 
Osmium  cat.,  64,  251 
Osmium  black,  583 

Osmium  oxide  hydrogenation  cat.,  80, 
583 

oxidation  cat.,  262,  271 
Oxal-acetic  acid  by  oxid,  268 
Oxalic  acid  cat.,  106 

dec.,  12,  855 

dec.  formic,  822 

esterif.,  758 

by  oxidation,  269 

oxidised,  246 

retarder,  11 
Oxalic  esters  dec.,  873 
Oxamide,  105,  312 
Oxidation,  64,  150,  152,  244-277 

catalysts,  59,  60,  100,  152,  162,  245- 
267 

by  chlorates,  271 

with  gaseous  oxygen,  244-267 

by  hydrogen  peroxide,  268 

by  hypochlorites,  270 

by  nitric  acid,  269n 

by  nitrobenzene,  277 


by  permanganates,  275 

by  persulphates,  276 

by  sulphur  trioxide,  272 

of  oils,  265 

of  phenols,  11 
Oxides,  carriers  for,  Pd  946 

catalysts,  73,  75,  784,  789,  807-809, 
813,  823,  837,  848,  858,  906,  921,  934 

in  cracking,  906,  934 

dec.  hydrocarb.,  906,  921,  934 

dehydrogenation  cats.,  638,  789 

hydrogenation  cats.,  598 

ketone  cats.,  848 

prep,  of,  76 

Oxides  of  carbon  hydrogenated,  504 
Oxides  of  nitrogen  cats.,  269n 

hydrogenated,  374 
Oximes  hydrogenated,  383,  514 

hydrolyzed,  332 
Oxygen  absorbed  by  C,  1806,  by  Au,  Pt 

and  Ag  137 

Oxygen  in   catalysts,    165,   563,   563n, 
943n 

in  Pt  black,  563 
Oxygenation  of  cat.,  943n,  947n 

Palladium  absorbs  hydrogen,  136,  150, 
165 

on  alcohols,  669 

on  aldehydes,  623 

amount  of  required,  951 

black,  251,  562,  573-579,  822 

cat.,  65,  126,  269n 

colloidal,  71,  141,  54^-555,  604 

colloidal  prep,  of,  71 

dehydrogenation  cat.,  648,  649,  651, 
669,  824 

hydrogenation  cat.,  534,  536-595 

in  hydrogenation  of  fats,  946 

poisoned,  1800 

polymeriz.,  212 

sponge,  604 

temp,  of  use,  952 
Palladium  black,  251,  562,  573-579,  822 

palladium  hydride,  150 
Palladium  sponge,  604 
Palladous  chloride,  562 
Palm  oil  bleached,  265 
Palmitic  esters,  937 
Parabutanal  formed,  223 
Paraldehyde  cond.,  801 


SUBJECT  INDEX 


397 


crotonized,  795,  801 

depolymerized,  234 

formed,  82,  104,  222,  223,  724 
Para-indene  formed,  217 
Parapropional,  223 
Peanut  oil,  938 

hardened,  966 
Pelargonic  acid  into  aldehyde,  852 

esterif.,  771 
Pennsylvania  petroleum  cracked,  911 

nature  of,  925 
Pentachlorpropane,  242 
Pentachlorpropylene  formed,  879 
Pentadecyl-benzene  hydrogenated,  569 
Pentamethylene  ring  hydrogenated,  474 
Penta-isobutanal  formed,  224 
Pentamethyl-benzene   dec.   F.   and  C., 

887 
Pentane  from  C2H2,  211 

dec.  by  Ni,  911 

formed,  211,  558,  565,  931 
Pentane-diol  dehydrated,  726 

by  hydrogenation,  595 
Pentane-thiol,  745 
Pentol-one,  439 
Perchlorbenzene  reduced,  404 
Perchlorethane  prep.,  289 
Perchlormethyl  mercaptan,  278n 
Perhydroanthracene,  29,  363,  483,  592 
Perkin's  syn.,  107 

Permanganates  as  oxidising  agents,  275 
Peroxides  as  intermediate  comps.,  150- 

153 

Persulphates  oxid.  agts.,  276 
Perylene,  685 
Petroleum  cracked,  254n 

by  Aids,  935 

formation,  506,  925-928 
Phellandrene,  198 
Phenanthrene  cond.,  806 

from  cracking,  909 

hydrogenated,  484,  642,  Ni  592,  Pd 

536,  579,  Pt  571 
Phenanthridene  oxidised,  270 

by  oxidation,  270 
Phenetol,  464 
Phenol  from  benzene,  150,  843 

from  bromphenols,  405 

from  chlorphenols,  404 

dehydrated,  16,  785 

by  diazo,  606 


by  dehydrogenation,  642 

ethers  of  formed,  75,  904,  785-789 

formed,  150,  293,  404,  405,  843 

hydrogenated,  120,  444,  456,  Ni  603, 
Pt569 

by  hydrogenation,  381 

by  oxidation,  263,  268 

into  thiophenol,  791 
Phenol  ethers  formed,  785-789 

hydrogenated,  494 
Phenols  with  aldehydes,  792 

condensed,  803 

dehydrated,  785,  789 

hydrogenated,  370,  456,  603 

nitrated,  269n 
Phenolic  glucosides,  793 
Phenylactaldehyde  by  dehydrogenation, 
657 

hydrogenated,  Pd  549,  Pt  560 
Phenyl  acetate  dec.,  871 
Phenylacetic  acid  into  aid.,  853 

dec.,  830,  839 

esterif.,  756-758 

hydrogenated,  471 

into  ketone,  843-845,  850 
Phenyl-acetylene     hydrogenated,     451, 

Cu520,Pd548 
Phenyl-alkyl  ethers  formed,  789 

hydrogenated,  464 
Phenylation  of  amines,  632 
Phenyl-benzyl  carbinol  dehydrated,  714 
Phenyl  bromide  in  syn.,  901,  904 
Phenyl-butyl  chloride  in  F.  and  C.  syn., 

897 

Phenyl-carvacryl  ether,  788 
Phenyl  chloride  in  syn.,  904 
Phenyl-p.cresyl  carbinol  red.,  369 
Phenyl-cresyl  ethers,  788 
Phenyl-p.cresyl-methane  by  hydrogena- 
tion, 369 

Phenyl-cyclohexane,  452,  475 
Phenyl-cyclopentane  by  F.  and  C.  syn., 

897 
Phenyl-cyclohexane  formed,  889 

hydrogenated,  475 
Phenylene  diamines  by  hydrogenation, 

380 

Phenylene-naphthalene  oxides,  788 
Phenylene  sulphide  formed,  295 
Phenyl  esters  dec.,  871 
Phenyl  ether,  338,  785-787 


398 


SUBJECT  INDEX 


hydrogenated,  494,  589 

formed,  59,  75,  786,  904 
Phenyl  ethers,  785-788 
Phenylethyl  alcohol  dehydrogenated,  657 

hydrogenated,  369 

by  hydrogenation,  560 
Phenylethyl  chloride  in  F.  and  C.  syn., 

897 

Phenyl-ethylene  hydrogenated,  415,  451, 
516 

by  hydrogenation,  520 
Phenyl-ethylene    hydrocarbons    hydro- 
genated, 415 

Phenyl-ethyl  ketone  hydrogenated,  539 
Phenyl-glycolic  acid  esterif.,  756 
Phenylhydrazine  dec.,  91,  611 

from  phenylhydrazones,  332 

hydrogenated,  497 

negative  cat.,  11 
Phenylhydrazones  dec.,  633,  635 

hydrol.,  332 

Phenyl-hydroxy-crotonic  acid,  203 
Phenyl  iodide  in  syn.,  904 
Phenyl-isocrotonic    acid   hydrogenated, 

417 

Phenyl  isocyanate  hydrogenated,  495 
Phenyl-naphthyl-amine,  632 
Phenyl-naphthyl  ketone  hydrogenated, 

685 

Phenyl-nitrosamine  formed,  206 
Phenyl  oxide  by  diazo,  59 

formed,  75,  338,  785-787,  904 

hydrogenated,  494,  589 

hydrol.,  16,  338 
Phenyl-naphthyl  ethers,  788 
Phenyl-pentyl    chloride    in  F.  and   C. 

syn.,  897 

Phenyl-propiolic  acid  hydrogenated,  548 
Phenyl-propionic  acid,  417, 546, 560, 580, 
581,  594,  601 

dec.,  839 

into  ketone,  844 
Phenyl-propyl  alcohol,  560,  568 
Phenyl-propylene  by  hydrogenation,  384 
Phenyl-propyl-pentane    by    hydrogena- 
tion, 415 
Phenyl-propyl-pentene      hydrogenated, 

415 

Phenyl-pyridines,  807 
Phenyl  sulphide  formed,  295 
Phorone  by  cond.,  797 


hydrogenated,  420,  Pd  547,  549,  Pt 

567 

Phosgene  formed,  134,  282,  282n,  284 
Phosphine  cat.,  780 

cat.  poison,  180o 

formed,  700 

Phosphoric  acid  cat.,  687,  689,  691,  696 
Phosphorus  cat.,  46,  687 

chlorination  cat.,  281 

oxidised,  150 

toxic  to  cats.,  115,  116 
Phosphorus,  red  dehydration  cat.,  700 
Phosphorus     trichloride     chlorination 

cat.,  281 
Phthalemes,  90 
Phthalic  acid  esterif.,  756 

hydrogenated,  392,  Ni  590,  Pt  563,  569 

by  oxid.,  273 
Phthalic  anhydride  cond.,  107 

by  oxid.,  260n,  273 
Phthalid  by  hydrogenation,  392 
Phthalimide  hydrogenated,  569 
Phthalophenone  by  F.  and  C.,  893 
Phthalyl-acetic  acid,  107 
Phthalyl  chloride  in  F.  and  C.  syn.,  893 
Physical  cond.  of  cat.,  41,  53-55,  76-80, 

703 

Physical  theory  of  catalysis,  131  et  seq. 
Phytane,  565 

Phytene  hydrogenated,  565 
Phytol  hydrogenated,  565 
Picoline,  680 
Pinacoline,  724 
Pinacones,  195,  724,  726 
Pinane,  552,  591,  594 
Pinene  cracked,  909 

dec.,  235,  909,  922,  923 

dehydrogenated,  664 

hydrated,  307 

hydrogenated,  477,  Cu  594,  Ni  591, 
Pd  552,  Pt  570 

isom.,  198 

polym.,  216 
Piperidine,  486,  555,  561 

alkylated,  741 

cat.,  804,  836 

dehydrogenated,  647 

in  vulc.  of  rubber,  104 
Piperonal  hydrogenated,  568 
Piperonal-acetone  hydrogenated,  565 
Piperonyl-acrylic  acid  hydrogenated,  601 


SUBJECT  INDEX 


399 


Piperonyl-propionic  acid,  601 
Piperylene  by  dehydration,  726,  784 

polym.,  213 
Pittsburgh  gas,  928 
Platinum  absorbs  O2,  137 

asbestos,  247 

catalyst,  61,  75,  126,  180c,  342,  539, 
563n,  615,  829 

in  combustion  anal.,  250 

in  cracking,  906 

dec.  acetylene,  913,  914,  920 

dec.  alcohols,  668 

dec.  aids.,  622 

dec.  ethylene,  912 

dec.  formic  esters,  867 

dehydrogenation  cat.,  636,  637,  643, 
649,  651,  668 

hydrogenation  cat.,  524-535,  945 

moss,  524 

oxidation  cat.,  4,  15,  61,  154,  235,  245, 
255,  249,  250,  255,  256 

oxidation  cat.  for  SOz,  4 

poisoned,  180o 

spiral,  829 

wire,  etc.,  249 
Platinum  black  activity  of,  63 

cat.,  235,  246,  247,  445,  562 

dec.  H2O2,  2 

deoxidising,  14 

heat  weakens,  63 

hydrogenation  cat.,  344,  524,  563-572 

oxidation  cat.,  1,  14 

poisoned,  117,  947n 

preparation,  61 
Platinum  chloride  cat.,  635 
Platinum,  colloidal,  69,  72, 141,  248,  544, 
556-561 

poisoned,  116 
Platinum  moss,  cat.,  524 
Platinum  sponge  cat.,  193,  245,  342,  445, 

524,  637,  824 

Poisoning  of  catalysts,  112  et  seq.,  180o- 
180s,  946,  947n 

of  Ni  cat.,  112,  598 

of  Pt  cat.,  116 
Poly-alcohols  dehydrogenated,  680,  723, 

727 

Poly-aldehydes  formed,  222 
Poly-alkyl-benzenes  dec.,  887 
Poly-ethyl-benzenes    dec.    F.    and   C., 

888 


Polycyclic  hydrocarbons  hydrogenated, 

432 

Polymerization,  89,  209-233 
Polymethylene  hydrocarbons,  535,  926, 

927 
Polymethylene  rings  hydrogenated,  Pt 

535 

Polyphenols  hydrogenated,  460 
Polyphenyl     hydrocarbons     hydrogen- 
ated, 452 

Polysaccharides  hydrol.,  323 
Polyterpenes  from  cracking,  909 
Polyvalerylene  formed,  212 
Poppyseed  oil,  938,  966 

hardened,  966 
Porous  substances,  139 
Potash  as  cat.,  611,  795 
Potassium    cat.    polym.    hydrocarbons, 

213,  232 

Potassium  acetate  cat.,  107 
Potassium  bisulphate  cat.,  97,  687,  725 

cat.  esterif.,  759,  760,  783 
Potassium  chloride  cat.,  876 
Potassium  cyanide  in  aldolization,  95 

cat.,  230 

toxic  to  Pt,  117 

Potassium  copper  cyanide  cat.,  95 
Potassium  ferricyanide  reduced  with  Pt, 

165 

Potassium  formate,  823 
Potassium  hydroxide  cat.,  799 
Potassium  iodide  cat.,  94 
Potassium  soaps  toxic  to  cats.,  115 
Preparation  of  catalysts,  54r-56,  58,  59, 
77,  78,  598,  606,  655,  704,  705,  941, 
942 
Pressure,  effect  of,  30 

on  dehydration,  711 

on  hydrogenation,  946,  956 

on  hydrolysis,  317 

on  inversion  of  sugars,  324 
Primary  alcohols  dehydrogenated,  650 
Promoters,  180s-180w 
Propane  from  ethyl  acetate,  18Q/ 

by  hydrogenation,  414,  472,  912 
Propane-thiol,  745 
Propenol  hydrogenated,  416 
Propionamide  hydrogenated,  386 
Propionic  acid  dec.,  838 

esterif.,  751,  771 

by  hydrogenation,  417 


400 


SUBJECT  INDEX 


into  ketone,  840,  842-845 
Propionic  aldehyde,  416,  419,  658,  664, 
668,  680,  839 

cond.,  795,  808 

crotonized,  795 

dec.,  Cu  621,  Ni  620,  Pd  623,  Pt  622 

into  ester,  228 

formed,  208,  249 

hydrogenated,  432 

by  oxidation,  249 

polym.,  223 
Propionic     aldehyde     phenylhydrazone 

dec.,  633 

Propionic  anhydride  into  ketone,  857 
Propionic  esters  dec.,  863,  871 
Propionitrile  cat.,  605 

polym.,  231 
Propionyl  chloride  cond.,  902 

into  nitrile,  813 

Propiophenone-oxime  hydrogenated,  384 
Propyl  acetate  dec.,  861 
Propyl-acetylene  formed,  192 
Propyl  alcohol,  416,  419,  558,  680,  740, 
741 

into  acetal,  780 

into  amine,  732 

dehydrated,  691,  694,  700,  713,  715- 
717,  719 

dehydrogenated,  656,  MnO  672,  Ni 
664,  Pt  668 

esterif.,  751,  771,  773,  775 

by  hydrogenation,  416 

oxidised,  249,  254,  268 
Propyl-amine  from  ale.,  733 

by  hydrogenation,  382 
Propyl-benzene  by  hydrogenation,  384, 

448,  539,  560 
Propyl  benzoate,  766 
Propyl  bromide  isom.,  199 
Propyl  chloride  dec.,  877 

isom.,  199 

Propyl  cyanide  as  cat.,  605 
Propyl-cyclohexane,  449,  590 
Propyl  formate,  773 

Propylene,  691,  694,  696,  700,  713,  716, 
735 

from  CjHj,  916 

dec.,  Ni  912 

formed,  877,  916 

hydrated,  306n 

hydrogenated,  414,  515,  526 


Propyl  ether,  691,  694 
Propyl  iodide,  605 
Propyl-isoamyl-amine,  738 
Propyl  malonate  dec.,  873 
Propyl  mercaptan,  744 
Propyl-methoxy-cyclohexanol,  569 
Propyl-methoxy-phenol,  603 
Propyl  nitrite  hydrogenated,  382 
Propyl  oxalate  dec.,  873 
Propyl  phenyl  ether,  789 
Propyl-piperidine,  741 
Propyl  propionate  from  aid.,  228 

dec.,  861 

by  esterif.,  751 
Propyl  succinate  dec.,  873 
Protocatechuic  aid.,  by  oxid.,  268 
Pseudocumene  hydrogenated,  447 

isom.,  888 
Pseudoionone,  800 
Pseudomorphine  by  oxid.,  268 
Pulegomenthol,  436,  567 
Pulegomenthone,  421,  436 
Pulegone,  dehydrogenated,  645 

hydrogenated,  421,  Ni  591,  Pd  552, 

Pt  567 
Pumice  cat.,  811,  828 

carrier,  126,  598 
Purification  of  oils  for  hydrogenation, 

947-949 
Pyridine  cat.,  187,  224,  836 

by  dehydrogenation,  647 

in  F.  and  C.  syn.,  893 

hydrogenated,  486,  Pd  555,  Pt  561 

oxidised,  257 

sulphonated,  816 

in  syn.,  893,  901 
Pyridine-carbonic    acid    hydrogenated, 

561 

Pyridine  homologs  hydrogenated,  561 
Pyridyl-phenyl  ketone  by  F.  and  C.  syn., 

893 
Pyrocatechol  hydrogenated,  370,  461 

by  oxid.,  268 
Pyrogallol  hydrogenated,  462 

oxidised,  150 

Pyrogenetic  equilibria,  905 
Pyrography,  249n 
Pyromucic  aid.  hydrogenated,  434 
Pyrone  formed,  835 
Pyrrol,  686,  807 

alkylated,  742 


SUBJECT  INDEX 


401 


hydrogenated,  486,  571 
Pyrrols  cond.,  803,  805 
Pyrrolidine,  429,  485,  571 

Quantity  of  cat.,  32 
Quercetine  by  hydrol.,  328 
Quinaldine  hydrogenated,  488 
Quinalizarine  by  oxid.,  274 
Quinidine  hydrogenated,  555 
Quinine  as  cat.,  836 

hydrogenated,  604 
Quinine  sulphate  hydrogenated,  572 
Quinite,  461,  589 

dehydrated,  723 
Quinizarine  by  oxid.,  274 
Quinoline  as  cat.,  187,  793,  836 

by  dehydrogenation,  647 

in  F.  and  C.  syn.,  893 

hydrogenated,  488,  489,  Ni  592,  Pd 

555,  Pt  561 
Quinone  hydrogenated,  442 

by  oxidation,  276 
Quinones  hydrogenated,  442 

Radiation  theory  of  catalysis,  18Q? 
Reaction  tube  for  catalysts,  347 
Reciprocal  catalysis,  146 
Regeneration    of    catalysts,     123-125, 

563n,  932,  947n,  950 
Regeneration  of  thoria,  708n 
Resinous  substances  by  oxidation,  266 
Resorcine  cond.,  806 

hydrogenated,  370,  461 
Reversible  reactions,  19,  39 
Rhodium  cat.,  64 
Rhodium  black  cat.,  822 

in  hydrogenation,  581 
Ribonic  acid  formed,  187 
Riche*  gas.,  397 
Ricinoleic  acid,  937 
Ricinoleic  esters,  937 
Ring  formation,  82,  194,  684,  685,  727, 

896 
Rubber  syn.,  106,  213,  214,  784 

vulcaniz.,  104 

Ruberythric  acid  hydrogenated,  328 
Russian  petroleum  cracked,  934,  936 
Ruthenium  cat.,  64 
Ruthenium  black,  580 

Sabinene  hydrogenated,  570 


Saccharic  acid  dehydrated,  727 
Safrol  hydrogenated,  Ni  590,  Pt  565 
Salicine,  329 
Salicylic  acid  esterif.,  756-757 

by  hydrol.,  328 
Saligenine  by  hydrol.,  329 
Saliretine  by  hydrol.,  329 
Sand  cat.,  696,  811 
Sandmeyer  reaction,  91,  609 
Santonin  hydrogenated,  571 
Saponification,  17,  305,  337 

acid  radical  influence,  316-319 

of  esters,  337 

of  fats,  314,  319 

neutral  salt  influence,  317 

theory  of,  176 

Saturated  hydrocarbons  by  hydrogena- 
tion, 412-415 
Schlinck's  apparatus,  960 
Schwoerer's  apparatus,  959 
Sebacic  acid  into  ketone,  843 
Secondary  alcohols,  420 

dehydrogenated,  650,  659 

esterif.,  766,  775 

prep.,  435 

Secondary    amines   by   hydrogenation, 
383 

from  naphthols,  790 

prep.,  427,  732 

Selective  absorption  by  cats.,  ISOh 
Selenium  hydride  toxic  to  cats.,  180o 
Selex,  967n 

Separation  of  carbon,  613 
Sesame  oil,  938 

hardened,  966 

Sesquiterpenes  hydrogenated,  570 
Side  chains  hydrogenated,  Cu  594,  Ni 

590 

Siemens  gas,  397 

Silica  cat.,  75,  78, 540, 675,  676,  702, 811, 
825,  911 

dec.  formic  acid,  624 

ketone  cat.,  847 

prep.,  705 

Silica  gel  cat.,  75n,  180c,  772n 
Silicates  cat.,  99,  267 

ketone  cat.,  847 
Silver  absorbs  Oj,  137 
cat.,  60 

with  CO,  615 

dec.  H,0»,  34 


402 


SUBJECT  INDEX 


oxidation  cat.,  252,  254,  259 
Silver  chloride  cat.,  876 
Silver  colloidal,  70,  72 
Silver  nitrate  cat.,  276 
Silver  oxide  cat.,  276 
Silver  salts  in  nitration,  269n 
Size  of  grains,  35 
Skatol,  647 
Snow  drift,  967n 
Soda  dehydration  cat.,  795 
Sodium  isom.  cat.,  50 

polymer,  cat.,  50,  213,  231,  232 
Sodium  acetate  dehydration  cat.,  107, 
795 

esterif.  cat.,  748,  761 

polym.  aids.,  224 
Sodium  alcoholate  cat.,  340n 
Sodium  borate  cat.,  574 
Sodium  carbonate  to  neut.  oils,  948 
Sodium  chloride  cat.,  876,  954 
Sodium  formate  cat.,  822 
Sodium  hydroxide  dehydration  cat.,  795, 

798 

Sodium  methylate  cat.,  799 
Sodium  nitrate  effect  on  Ni,  947 
Sodium  sulphide  toxic  to  cats.,  947 
Sodium  thiosulphate  in  isom.,  182 
Solvent  naphtha  cracked,  909 
Solvents  as  cats.,  36,  37,  40 

in  hydrogenation,  599 

influence  of,  38-40,  18Qf 

influence  on  equilibra,  39 

influence  on  inversion  of  sugars,  324 

influence  on  reaction  velocity,  38 
Sorbic  acid  hydrogenated,  558 
Sorbite,  588,  595 
Sorbose  formed,  186 
Specificity  of  cats.,  142 
Spirocyclane  hydrogenated,  535 
Squibb's  method,  161 
Stabilizers,  13 
Stannic  chloride  acetylation  cat.,  240 

chlorination  cat.,  283,  288 

cond.  cat.,  243 

in  F.  and  C.  syn.,  899 
Stannic  oxide  ketone  cat.,  849 
Stannous  oxide  cat.,  288,  539,  676 

dec.  alcohols,  673 

dehydrogenation  cat.,  673,  824 
Starch  cat.,  269n 

hydrolyzed,  4,  323,  326 


State  of  cat.,  41,  53-55,  76-80 
Stearic  acid,  422,  515,  546,  558,  562,  577, 
587,  601 

into  ketone,  843,  847,  850 
Stearic  esters,  937 
Stearine,  937 
Stearone,  847 

Stearyl  chloride  hydrogenated,  575 
Stibine  dec.,  8 

toxic  to  cats.,  1800 
Stilbene  by  dehydration,  714 

hydrogenated,  415,  515 

by  hydrogenation,  548 
Stirring  in  hydrogenation,  587n,  601 
Stoichiometric  theory  of  catalysis,  180a 
Strontium  carbonate  cat.,  838 
Strychnine  hydrogenated,  555 
Styrene  from  acetylene,  914,  916 

formed,  241,  520,  548,  657,  889 

hydrogenated,  415,  451,  Cu  516,  Pd 

546,  Pt  569 
Suberic  acid,  566 

into  ketone,  843 
Succinic  acid  esterif.,  756 

by  hydrogenation,  546 
Succinic  anhydride  formed,  873,  874 

hydrogenated,  392 
Succinic  esters  decom.,  873,  874 
Succinimide,  312 

Succinoyl  chloride  in  F.  and  C.  syn.,  893 
Sucrose  hydrol.,  323,  324 
Sugar  oxid.,  269 
Sugars  formed,  236 

by  hydrol.,  323 

inverted,  175 

isom.,  186 

multirotation  of,  188 
Sulphates  effect  on,  Ni  947 
Sulphides,  743,  744 
Sulphocyanic  esters,  333 
Sulphonation,  815,  816 

aided  by  HgSO4,  102 
Sulphur  added,  295,  296 

catalyst,  6,  45,  630 

chlorine  cat.,  280 

eliminated  from  petroleum,  933 

toxic  to  cats.,  115,  116,  947 
Sulphur  compounds  in  hydrogenation, 
569 

toxic  to  cats.,  946 
Sulphur  dioxide  added,  87,  297 


SUBJECT  INDEX 


403 


cat.,  74 

oxidised  with  Pt  4,  247 

polym.  aids.,  222 
Sulphuric  acid  on  alcohols,  159 

catalyst,  687,  689,  691,  696,  713 

cond.  agt.,  795,  803 

inesterif.,   748,   749,   751,   752,  756, 
758 

on  formald.,  822 

in  hydration,  306,  308 

isom.  terpenes,  198 

manufacture,  32,  158 

by  oxidation,  258 
Sulphuric  acid  fuming  as  oxid.  agt.,  272- 

274 
Sulphur  trioxide  cat.,  12 

manuf.,  247 

oxidising  agt.,  272 
Sunlight  in  chlorination,  281n 
Surface,  importance  of,  35 
Sylvestrene  hydrogenated,  477 
Synthetic  tallow,  967 

Tagatose  formed,  186 
Talgol,  967 
Tallow,  938 

hardened,  966 
Talomucic  acid,  187 
Talose  formed,  186 
Tartaric  acid  esterif.,  756 

toxic  to  cats.,  115 
Tellurium  oxid.  cat.,  45,  251 
Tellurium  hydride  toxic  to  cats.,  180o 
Temperature  coef.  in  dehydration,  709 

coef .  of  reactions,  24,  25 

effect  on  hydrocarbons,  905 

of  hydrogenation,  361,  952 

of  prep,  of  cats.,  707n 

regulation,  348 
Terephthalic  acid,  648 
Terpenes  dec.,  922 

dehydrogenated,  643 

hydrogenated,  477,  Ni  591,  Pt  570 

isom.,  198 
Terpine,  307,  308 
Terpinene  formed,  198 
Terpineol  dehydrogenated,  645 

hydrogenated,  478,  552 
Terpinolene  formed,  198 
Tertiary  alcohols  esterif.,  778 
Tertiary  butyl  alcohol  oxidised,  249 


Tetra-acetyl-phenyl-glucoside,  793 

Tetra-amylene  formed,  211 

Tetrabromethane  in  F.  and  C.  syn.,  897 

Tetrachlorethane  dec.,  881 
formed,  199 
in  syn.,  903 

Tetrachlorethylene  formed,  879 

Tetracosene  formed,  210 

Tetra-ethyl-ammonium  iodide,  38 

Tetrahydro-acenaphthene,  482 

Tetrahydro-anthracene,    29,    363,    483, 
592,  642 

Tetrahydrobenzoic  acid,  476 

Tetrahydrocarvone,  552,  567 

Tetrahydrocolchicine,  555 

Tetrahydrodoremone,  570 

Tetrahydrofurfuryl-ethyl  carbinol,  487 

Tetrahydroionones,  554 

Tetrahydro-methyl-furfurane,  487 

Tetrahydro  -  methyl  -  naphthalene  -  car- 
bonic acid,  563 

Tetrahydronaphthalene,  379,  481,  481n, 
571,  592,  594 

Tetrahydronaphthoic  acid,  594 

Tetrahydronaphthalid,  563 

Tetrahydrophenanthrene,  484,  536,  579, 
592,  642 

Tetrahydrophenol,  723 

Tetrahydropiperine,  555 

Tetrahydroquinoline,  488,  561,  592 
dehydrogenated,  647 

Tetrahydrosantonine,  571 

Tetrahydrostrychnine,  555 

Tetrahydroterephthalic  acid,  648 

Tetrahydroxyanthracene  oxid.,  274 

Tetrahydroxyflavanol  by  hydrol.,  328 

Tetra-isobutanal  formed,  224 

Tetralin,  481n 

Tetramethyl-benzene  dec.,  F.  and  C., 
887 

Tetramethyl-diamino-benzhydrol  cond. , 
730 

Tetramethyl-leucaniline,  730 

Tetramethylene-diamine,  429 

Tetramethylene  ring  hydrogenated,  473 

Tetraphenylethane,  538,  662,  720 
hydrogenated,  453 

Tetraphenylethylene,  736 

Tetrolic  acid  hydrogenated,  546 

Thalium  cat.,  47 

Thalium  chloride  chlo.  cat.,  283 


404 


SUBJECT  INDEX 


Theories  of  catalysis,  129  et  seq.,  131, 

145,  180,  180a-180u 
Theory  of  dehydration,  785 
Theory  of  esterification,  752,  762,  763 
Theory  of  ester  decomp.,  859-864,  866, 

872 

Theory  of  poisoning  catalysts,  180o 
Thianthrene,  629 
Thiobenzophenone  syn.,  894 
Thiodinaphthyl-amines  formed,  296 
Thiodiphenyl-amine  formed,  296 
Thio-indigo  hydrogenated,  603 
Thiophene  formation,  686,  810 

toxic  to  cats.,  112,  947n 
Thiophenol  formed,  295 
Thiophenols  dec.,  629 

formed,  295 

Thiophosgene  in  F.  and  C.  syn.,  894 
Thiols  formed,  75,  743-746 
Thiourea  isom.,  207 
Thioureas,  630 

Thoria  catalyst,  16,  24,  75,  79,  143,  170, 
538,  676,  693,  700,  702,  707,  716, 
720,  731-738,  813 

aldehyde  cat.,  854 

dec.  chlorides,  881 

dec.  esters,  858,  861,  861n,  864-866, 
872,   873,    1806,    180/,    180.;,    180n 

dec.  formates,  870 

dehydration  cat.,  651,  743-746,  788, 
789,  791,  801,  808,  809 

dehydrogenation  cat.,  686 

esterif.  cat.,  764-766,  772 

hydrolysis  cat.,  337,  338 

lif e  of,  708 

ketone  cat.,  840,  844,  848,  850,  857 

mercaptan  cat.,  746 

mixed  cat.,  826 

preparation  of,  707n,  86  In 
Thorium  chloride  cat.,  90 
Thujane,  570 
Thujone  hydrogenated,  478,  552,  570 

isom.,  198 
Thymol,  ethers  of,  789 

formed,  645 

hydrogenated,  459 
Thymoquinol  hydrogenated,  463 
Thymoquinone  hydrogenated,  442 
Tin  chlorination  cat.,  47,  288 

dehydrogenation  cat.,  673,  824 
Tin  chlorides  acetylation  cat.,  240 


chlorination  cats.,  283,  288 

cond.  cat.,  243 
Tin  oxides  chlorination  cats.,  288 

dehydration  cats.,  702 
Titania  cats.,  75,   143,  337,  624,   693, 
702,  704,  709,  732 

aldehyde  cat.,  852 

in  cracking,  906,  934 

dec.,  alcohols,  1800 

dec.  esters,   1806,   ISO/,   18Q/,   180n, 
861n,  863,  864,  868 

dehydration  cat.,  825 

dehydrogenation  cat.,  686 

esterif.  cat.,  765,  767,  771,  772,  775 

hydrolyt.  cat.,  686 

ketone  cat.,  849 

mixed  cat.,  675,  676 

prep,  of,  704,  861n 
Tolane,  hydrogenated,  548 
Toluene,  465,  560,  590,  593,  641,  657, 
681 

brominated,  292,  293 

chlorinated,  278,  281,  285 

from  cracking,  908,  909 

from  cresoles,  370 

from  cymene,  930 

dec.  by  F.  and  C.,  887 

by  F.  and  C.  syn.,  884 

in  F.  and  C.  syn.,  899 

hydrogenated,  444,  447,  Pt  534,  560, 
569,  Rh  581,  Ru  580 

by  hydrogenation,  369,  388 

oxidised,  257,  260n,  263 

from  petroleum,  934 

from  pinene,  922 
sulphonated,  815n 

from  xylene,  930 
Toluic  acids  dec.,  830 

esterif.,  758,  766 

into  ketones,  848,  849 
Toluic  aldehydes  dec.,  623 

syn.,  298 
Toluic  esters  dec.,  864,  871 

hydrogenated,  471 

Toluidines,  497,  564,  630-632,  683,  684, 
790 

alkylated,  740 

hydrogenated,  467 

by  hydrogenation,  380 

manufacture  of,  512 

oxidised,  256 


SUBJECT  INDEX 


405 


Toluonitrile  hydrogenated,  428 
Toluquinone  hydrogenated,  442 
Tolyl-dimethyl  carbinol  hydrogenated, 

369,  465 

Toxic  substances  removed,  947-949 
Toxicity  of  CO,  953 
Toxicity  scale,  116 
Trade  names  of  hardened  oils,  967 
Trehalose  hydrol.,  323,  325 
Triacetin,  760 
Tri-amylene  formed,  211 
Tribromphenol,  293 

hydrogenated,  405 
Tributene  formed,  210 
Trichlorbenzene,  404 
Trichlor-tert.butyl  alcohol,  238 
Trichlorethylene  cond.,  242 

formed,  881 

Trichlorethyl  trichloracetate,  228 
Trichlorphenol,  404 
Tricyclohexyl-methane,  453 
Triethyl-amine  cond.,  38 

formed,  377,  427 

Triethyl-amine  hydrochloride  cat.,  783 
Triheptene,  519 
Tri-isoamyl-amine,  682 
Trimethyl-amine  cat.,  224 

formed,  377,  496 
Trimethyl-benzenes  dec.,  887 
Trimethyl    carbinol    dehydrated,    713, 
719 

esterif.,  776 

into  ether,  691 

formed,  306 

Trimethyl-cyclohexanes,  449 
Trimethylene  bromide,  605 
Trimethylene  ring  hydrogenated,  472 
Trimethyl-ethylene  dec.,  Ni,  912 

formed,  190 

hydrogenated,  414 

polym.,  210 
Trimethyl  -  hy droxy  -  butyl  -  cy clohexane, 

560 

Trimethyl-nonenone  hydrogenated,  420 
Trimethyl-pentane   by   hydrogenation, 

414 

Trimethyl-pyrazoline  formed,  196 
Trioxymethylene  into  acetal,  781 

cond.,  792,  806 

formed,  432 

in  syn.  rubber,  215 


Triphenyl  carbinol  reduced,  369 
Triphenylene,  646 

Triphenyl-methane   formed,    369,    728, 
890 

hydrogenated,  453 
Tungsten  as  promoter,  180s 

filament,  180e,  180p 
Tungsten,  blue  oxide,  cat.,  24,  693,  825 

dehydration  cat.,  651,  791 

on  formic  acid,  624 

mercaptan  cat.,  746 
Tungstic  oxide,  75 
Turpentine  oxid.,  151 
Types  of  hydrogenation  apparatus,  957, 
964 

Undecenal,  658 
Undecenyl  alcohol,  658 
Undecylenic  acid  hydrogenated,  417 
Undecylic  acid,  417 
Unsaturated  acids  esterif.,  756 

hydrogenated,  422 

isom.,  203 

Unsaturated  alcohols  hydrogenated,  416, 
418,  419 

into  sat.  aids.,  208 

into  cat.  ketones,  208 
Unsaturated  chlorides  dec.,  876 
Unsaturated  esters,  937 
Unsaturated    hydrocarbons,    743,    764, 
802,  866 

dec.,  912 

formed,  75,  142,  169,  695  et  seq.,  871, 
872,  876,  878 

hydrated,  305 
Unsaturated  ketones  hydrogenated,  420, 

602 
Uranium  in  drying  oils,  266 

as  promoter,  180s 
Uranium  chlorides  cats.,  90,  283 
Uranium  oxide  cat.,  75,  260,  702 

dec.  alcohols,  142 

ketone  cat.,  840,  849 

oxidation  cat.,  259 

Uranous    oxide    cat.,    675,    676,   726, 
825 

dehydration  cat.,  791 

mercaptan  cat.,  746 
Uranium  soaps  toxic  to  cats.,  115 
Urea  acetylated,  87 
Urethane  oxid.,  259 


406 


SUBJECT  INDEX 


Valeric  acid  from  alcohol,  150 

into  ketone,  842,  845 
Valeric  esters  dec.,  863 
Valerolactone,  437 
Valerone,  547,  549 
Valerylene  polym.,  212 
Vanadium  chloride  chlorination  cat.,  283 
Vanadium  pentoxide  cat.,  269,  676,  693, 
702,  828 

oxidation  cat.,  260,  260n,  262n,  271 
Vanadium  sulphate  in  sulphonation,  816 
Vanadous  oxide  cat.,  675 
Vanilline  acetylated,  240 

hydrogenated,  568 

by  oxidation,  191,  249 
Vanilline  triacetate,  240 
Various  rings  hydrogenated,  592,  603 
Velocity  of  catalytic  reactions,  23 
Vinyl  bromide  in  F.  and  C.  syn.,  889 
Vinyl-trimethylene  hydrogenated,  577 
Volume  of  hydrogen  req.  by  various  oils, 
955 

Walls  of  vessel  as  cat.,  244n 
Water  as  cat.,  73,  249 

effect  on  dehydration,  710 

effect  on  ethylene  prep.,  ISOh 

effect  on  hydrogenation,  949 

neg.  cat.,  12 
Water  gas,  398,  402 

for  hydrogenation,  953 

reducing  agent,  511 
Wilbuschewitch's  apparatus,  961 
Williamson's  reaction,  159,  169 
Whale  oil,  938 

effect  on  cat.,  947 
Woltman's  apparatus,  964 
Wurtz  syn.,  11 

Xylenes  brominated,  292 
chlorinated,  278,  285 
add  CO,  298 
from  cracking,  908,  909 
from  cymene,  930 
dec.,  by  A1C1,  887,  930 
by  dehydrogenation,  641 


hydrogenated,  444,  447,  534,  569 

from  pinene,  922 

isomer.,  888 
Xylenols,  ethers  of,  786,  789 

hydrogenated,  458 
Xylonic  acid  formed,  187 
Xylose,  188 

Zinc  cat.  cond.  cat.  52,  795 

dec.  alcohols,  670 

dehydrogenation  cat.,  670,  678 

in  F.  and  C.   syn.,  899 

hydrogenation  cat.,  595 

oxidation  cat.,  269n 

polym.  aids.,  219 

toxic  to  cats.,  115,  946 
Zinc  bromide  bromination  cat.  293 

isom.  cat.,  200 
Zinc  carbonate  cat.,  824 
Zinc  chloride  bromination  cat.,  293 

cat.,  6,  89,  234,  240,  283,  633,  635,  687, 
689,  691,  695,  698 

cond.  cat.,  795,  796,  803 

esterif.  cat.,  748,  761,  795 

in  F.  and  C.  syn.,  899 

hydrol.  cat.,  330 

polym.  cat.,  211,  216,  222 
Zinc  hydroxide  isom.  sugars,  186 
Zinc  organo-compounds,  304 
Zinc  oxide  cat.,  75,  143,  539,  675,  676 

in  cracking,  906,  934 

dec.  formates,  869 

dehydration  cat.,  702 

dehydrogenation  cat.,  824 

hydration  cat.,  310 

ketone  cat.,  841,  849 
Zirconia,  amine  cat.,  732 

cat.,  746,  791,  825,  840,  849 

esterification  cat.,  772n 

dec.  formic  ac.,  624 

dehydration  cat.,  791 

dehydrogenation  cat.,  676,  693 

ketone  cat.,  840,  849 

mercaptan  cat.,  746 

mixed  cat.,  651,  675,  702 


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